From 0c3ce7943dbaae422211ea12bd8c4a7d8e7d6fa9 Mon Sep 17 00:00:00 2001
From: Jon Gjengset <jon@thesquareplanet.com>
Date: Mon, 18 May 2020 14:12:10 -0400
Subject: [PATCH 01/21] Expose unilateral mailbox flag changes

This is a backwards incompatible change, since it adds a variant to a
public enum.
---
 src/parse.rs     | 11 +++++++++--
 src/types/mod.rs |  9 +++++++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/parse.rs b/src/parse.rs
index b2dc002..b7418a9 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -322,8 +322,15 @@ fn handle_unilateral<'a>(
         Response::MailboxData(MailboxDatum::Recent(n)) => {
             unsolicited.send(UnsolicitedResponse::Recent(n)).unwrap();
         }
-        Response::MailboxData(MailboxDatum::Flags(_)) => {
-            // TODO: next breaking change:
+        Response::MailboxData(MailboxDatum::Flags(flags)) => {
+            unsolicited
+                .send(UnsolicitedResponse::Flags(
+                    flags
+                        .into_iter()
+                        .map(|s| Flag::from(s.to_string()))
+                        .collect(),
+                ))
+                .unwrap();
         }
         Response::MailboxData(MailboxDatum::Exists(n)) => {
             unsolicited.send(UnsolicitedResponse::Exists(n)).unwrap();
diff --git a/src/types/mod.rs b/src/types/mod.rs
index 4a789e5..9757680 100644
--- a/src/types/mod.rs
+++ b/src/types/mod.rs
@@ -262,6 +262,15 @@ pub enum UnsolicitedResponse {
     /// sequence numbers 9, 8, 7, 6, and 5.
     // TODO: the spec doesn't seem to say anything about when these may be received as unsolicited?
     Expunge(Seq),
+
+    /// An unsolicited [`FLAGS` response](https://tools.ietf.org/html/rfc3501#section-7.2.6) that
+    /// identifies the flags (at a minimum, the system-defined flags) that are applicable in the
+    /// mailbox. Flags other than the system flags can also exist, depending on server
+    /// implementation.
+    ///
+    /// See [`Flag`] for details.
+    // TODO: the spec doesn't seem to say anything about when these may be received as unsolicited?
+    Flags(Vec<Flag<'static>>),
 }
 
 /// This type wraps an input stream and a type that was constructed by parsing that input stream,

From cf4aed569b62dfcc9dea0b54778bba4886de06d3 Mon Sep 17 00:00:00 2001
From: Jon Gjengset <jon@thesquareplanet.com>
Date: Mon, 18 May 2020 14:12:34 -0400
Subject: [PATCH 02/21] Make UnsolicitedResponse non_exhaustive

That way, as we discover additional unilateral responses in the future,
we won't have to make a breaking change to add them.
---
 src/types/mod.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/types/mod.rs b/src/types/mod.rs
index 9757680..8a13903 100644
--- a/src/types/mod.rs
+++ b/src/types/mod.rs
@@ -211,6 +211,7 @@ pub use imap_proto::StatusAttribute;
 /// Note that `Recent`, `Exists` and `Expunge` responses refer to the currently `SELECT`ed folder,
 /// so the user must take care when interpreting these.
 #[derive(Debug, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum UnsolicitedResponse {
     /// An unsolicited [`STATUS response`](https://tools.ietf.org/html/rfc3501#section-7.2.4).
     Status {

From 02ce8cb5118e77e0ff6287418074a954ba9acfc6 Mon Sep 17 00:00:00 2001
From: Jon Gjengset <jon@thesquareplanet.com>
Date: Mon, 18 May 2020 14:28:08 -0400
Subject: [PATCH 03/21] Bump MSRV for non_exhaustive

---
 azure-pipelines.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 5cc11d8..f9e126c 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -47,12 +47,12 @@ jobs:
  - job: msrv
    pool:
      vmImage: ubuntu-latest
-   displayName: "Minimum supported Rust version: 1.36.0"
+   displayName: "Minimum supported Rust version: 1.40.0"
    dependsOn: []
    steps:
      - template: install-rust.yml@templates
        parameters:
-         rust: 1.36.0
+         rust: 1.40.0
      - script: cargo check
        displayName: cargo check
  - job: integration

From 8be583a9f71371d970cdbd03ce87c578dccda6b6 Mon Sep 17 00:00:00 2001
From: mordak <todd@opennet.ca>
Date: Mon, 7 Dec 2020 23:43:19 -0500
Subject: [PATCH 04/21] CI: Only install components when needed. (#173)

---
 azure-pipelines.yml | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index de1917f..c0b9b84 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -25,9 +25,6 @@ jobs:
      - template: install-rust.yml@templates
        parameters:
          rust: $(rust)
-         components:
-           - rustfmt
-           - clippy
      - script: cargo check --all-targets
        displayName: cargo check
      - script: cargo test --examples
@@ -36,10 +33,16 @@ jobs:
        displayName: cargo test --doc
      - script: cargo test --lib
        displayName: cargo test --lib
-     - script: cargo fmt --all -- --check
+     - script: |
+         set -e
+         rustup component add rustfmt
+         cargo fmt --all -- --check
        displayName: cargo fmt --check
        condition: and(eq( variables['rust'], 'beta' ), eq( variables['Agent.OS'], 'Linux' ))
-     - script: cargo clippy -- -D warnings
+     - script: |
+         set -e
+         rustup component add clippy
+         cargo clippy -- -D warnings
        displayName: cargo clippy
        condition: and(eq( variables['rust'], 'beta' ), eq( variables['Agent.OS'], 'Linux' ))
  # This represents the minimum Rust version supported.

From ee56c8e42ba2fafd0270d16c248eb2dce3899248 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?=
 <mblarsen@users.noreply.github.com>
Date: Wed, 16 Dec 2020 00:25:38 +0800
Subject: [PATCH 05/21] feat: allow setting sent date on APPEND (#174)

Fixes #60
---
 src/client.rs             | 34 ++++++++++++++++++++++++-
 tests/imap_integration.rs | 53 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 1 deletion(-)

diff --git a/src/client.rs b/src/client.rs
index a47c401..26a1432 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -1,5 +1,6 @@
 use base64;
 use bufstream::BufStream;
+use chrono::{DateTime, FixedOffset};
 #[cfg(feature = "tls")]
 use native_tls::{TlsConnector, TlsStream};
 use nom;
@@ -1096,6 +1097,32 @@ impl<T: Read + Write> Session<T> {
         mailbox: S,
         content: B,
         flags: &[Flag<'_>],
+    ) -> Result<()> {
+        self.append_with_flags_and_date(mailbox, content, flags, None)
+    }
+
+    /// The [`APPEND` command](https://tools.ietf.org/html/rfc3501#section-6.3.11) can take
+    /// an optional FLAGS parameter to set the flags on the new message.
+    ///
+    /// > If a flag parenthesized list is specified, the flags SHOULD be set
+    /// > in the resulting message; otherwise, the flag list of the
+    /// > resulting message is set to empty by default.  In either case, the
+    /// > Recent flag is also set.
+    ///
+    /// The [`\Recent` flag](https://tools.ietf.org/html/rfc3501#section-2.3.2) is not
+    /// allowed as an argument to `APPEND` and will be filtered out if present in `flags`.
+    ///
+    /// Pass a date in order to set the date that the message was originally sent.
+    ///
+    /// > If a date-time is specified, the internal date SHOULD be set in
+    /// > the resulting message; otherwise, the internal date of the
+    /// > resulting message is set to the current date and time by default.
+    pub fn append_with_flags_and_date<S: AsRef<str>, B: AsRef<[u8]>>(
+        &mut self,
+        mailbox: S,
+        content: B,
+        flags: &[Flag<'_>],
+        date: impl Into<Option<DateTime<FixedOffset>>>,
     ) -> Result<()> {
         let content = content.as_ref();
         let flagstr = flags
@@ -1104,11 +1131,16 @@ impl<T: Read + Write> Session<T> {
             .map(|f| f.to_string())
             .collect::<Vec<String>>()
             .join(" ");
+        let datestr = match date.into() {
+            Some(date) => format!(" \"{}\"", date.format("%d-%h-%Y %T %z")),
+            None => "".to_string(),
+        };
 
         self.run_command(&format!(
-            "APPEND \"{}\" ({}) {{{}}}",
+            "APPEND \"{}\" ({}){} {{{}}}",
             mailbox.as_ref(),
             flagstr,
+            datestr,
             content.len()
         ))?;
         let mut v = Vec::new();
diff --git a/tests/imap_integration.rs b/tests/imap_integration.rs
index 0a8bf76..b37f3f3 100644
--- a/tests/imap_integration.rs
+++ b/tests/imap_integration.rs
@@ -1,8 +1,10 @@
+extern crate chrono;
 extern crate imap;
 extern crate lettre;
 extern crate lettre_email;
 extern crate native_tls;
 
+use chrono::{FixedOffset, TimeZone};
 use lettre::Transport;
 use std::net::TcpStream;
 
@@ -330,3 +332,54 @@ fn append_with_flags() {
     let inbox = c.search("ALL").unwrap();
     assert_eq!(inbox.len(), 0);
 }
+
+#[test]
+fn append_with_flags_and_date() {
+    use imap::types::Flag;
+
+    let to = "inbox-append3@localhost";
+
+    // make a message to append
+    let e: lettre::SendableEmail = lettre_email::Email::builder()
+        .from("sender@localhost")
+        .to(to)
+        .subject("My third e-mail")
+        .text("Hello world")
+        .build()
+        .unwrap()
+        .into();
+
+    // connect
+    let mut c = session(to);
+    let mbox = "INBOX";
+    c.select(mbox).unwrap();
+    // append
+    let flags: &[Flag] = &[Flag::Seen, Flag::Flagged];
+    let date = FixedOffset::east(8 * 3600)
+        .ymd(2020, 12, 13)
+        .and_hms(13, 36, 36);
+    c.append_with_flags_and_date(mbox, e.message_to_string().unwrap(), flags, Some(date))
+        .unwrap();
+
+    // now we should see the e-mail!
+    let inbox = c.uid_search("ALL").unwrap();
+    // and the one message should have the first message sequence number
+    assert_eq!(inbox.len(), 1);
+    let uid = inbox.into_iter().next().unwrap();
+
+    // fetch the e-mail
+    let fetch = c.uid_fetch(format!("{}", uid), "(ALL UID)").unwrap();
+    assert_eq!(fetch.len(), 1);
+    let fetch = &fetch[0];
+    assert_eq!(fetch.uid, Some(uid));
+    assert_eq!(fetch.internal_date(), Some(date));
+
+    // and let's delete it to clean up
+    c.uid_store(format!("{}", uid), "+FLAGS (\\Deleted)")
+        .unwrap();
+    c.expunge().unwrap();
+
+    // the e-mail should be gone now
+    let inbox = c.search("ALL").unwrap();
+    assert_eq!(inbox.len(), 0);
+}

From 3386c267116605c53a402e98e72948ecf277f9a1 Mon Sep 17 00:00:00 2001
From: Jon Gjengset <jon@thesquareplanet.com>
Date: Tue, 15 Dec 2020 08:29:57 -0800
Subject: [PATCH 06/21] Bump version for append_with_date

---
 CHANGELOG.md | 14 +++++++++++++-
 Cargo.toml   |  6 +++---
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b48ebcb..ebfdbe4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Removed
 
+## [2.4.0] - 2020-12-15
+### Added
+
+ - `append_with_flags_and_date` (#174)
+
+## [2.3.0] - 2020-08-23
+### Added
+
+ - `append_with_flags` (#171)
+
 ## [2.2.0] - 2020-07-27
 ### Added
 
@@ -24,5 +34,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  - MSRV increased
  - Better documentation of server greeting handling (#168)
 
-[Unreleased]: https://github.com/jonhoo/rust-imap/compare/v2.2.0...HEAD
+[Unreleased]: https://github.com/jonhoo/rust-imap/compare/v2.4.0...HEAD
+[2.4.0]: https://github.com/jonhoo/rust-imap/compare/v2.2.0...v2.4.0
+[2.3.0]: https://github.com/jonhoo/rust-imap/compare/v2.2.0...v2.3.0
 [2.2.0]: https://github.com/jonhoo/rust-imap/compare/v2.1.2...v2.2.0
diff --git a/Cargo.toml b/Cargo.toml
index e4f5388..1dd1d68 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "imap"
-version = "2.3.0"
+version = "2.4.0"
 authors = ["Matt McCoy <mattnenterprise@yahoo.com>",
            "Jon Gjengset <jon@thesquareplanet.com>"]
 documentation = "https://docs.rs/imap/"
@@ -31,14 +31,14 @@ regex = "1.0"
 bufstream = "0.1"
 imap-proto = "0.10.0"
 nom = "5.0"
-base64 = "0.12"
+base64 = "0.13"
 chrono = "0.4"
 lazy_static = "1.4"
 
 [dev-dependencies]
 lettre = "0.9"
 lettre_email = "0.9"
-rustls-connector = "0.12.0"
+rustls-connector = "0.13.0"
 
 [[example]]
 name = "basic"

From 469d338d5da0cb8c3996614b42677428abbb9aaa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Thu, 17 Dec 2020 00:20:48 +0800
Subject: [PATCH 07/21] refactor: combine all append_* + introduce
 AppendOptions

---
 src/client.rs             | 54 ++++++++++++++++++---------------------
 tests/imap_integration.rs | 25 ++++++++++++++----
 2 files changed, 45 insertions(+), 34 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index 26a1432..167ea70 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -84,6 +84,15 @@ pub struct Connection<T: Read + Write> {
     pub greeting_read: bool,
 }
 
+/// A set of options for the append command
+#[derive(Default)]
+pub struct AppendOptions<'a> {
+    /// Optional list of flags
+    pub flags: Option<&'a [Flag<'a>]>,
+    /// Optional internal date
+    pub date: Option<DateTime<FixedOffset>>,
+}
+
 // `Deref` instances are so we can make use of the same underlying primitives in `Client` and
 // `Session`
 impl<T: Read + Write> Deref for Client<T> {
@@ -1078,10 +1087,9 @@ impl<T: Read + Write> Session<T> {
     /// Specifically, the server will generally notify the client immediately via an untagged
     /// `EXISTS` response.  If the server does not do so, the client MAY issue a `NOOP` command (or
     /// failing that, a `CHECK` command) after one or more `APPEND` commands.
-    pub fn append<S: AsRef<str>, B: AsRef<[u8]>>(&mut self, mailbox: S, content: B) -> Result<()> {
-        self.append_with_flags(mailbox, content, &[])
-    }
-
+    ///
+    /// -- TODO merge docs possibly move to AppendOptions
+    ///
     /// The [`APPEND` command](https://tools.ietf.org/html/rfc3501#section-6.3.11) can take
     /// an optional FLAGS parameter to set the flags on the new message.
     ///
@@ -1092,48 +1100,36 @@ impl<T: Read + Write> Session<T> {
     ///
     /// The [`\Recent` flag](https://tools.ietf.org/html/rfc3501#section-2.3.2) is not
     /// allowed as an argument to `APPEND` and will be filtered out if present in `flags`.
-    pub fn append_with_flags<S: AsRef<str>, B: AsRef<[u8]>>(
-        &mut self,
-        mailbox: S,
-        content: B,
-        flags: &[Flag<'_>],
-    ) -> Result<()> {
-        self.append_with_flags_and_date(mailbox, content, flags, None)
-    }
-
-    /// The [`APPEND` command](https://tools.ietf.org/html/rfc3501#section-6.3.11) can take
-    /// an optional FLAGS parameter to set the flags on the new message.
     ///
-    /// > If a flag parenthesized list is specified, the flags SHOULD be set
-    /// > in the resulting message; otherwise, the flag list of the
-    /// > resulting message is set to empty by default.  In either case, the
-    /// > Recent flag is also set.
-    ///
-    /// The [`\Recent` flag](https://tools.ietf.org/html/rfc3501#section-2.3.2) is not
-    /// allowed as an argument to `APPEND` and will be filtered out if present in `flags`.
+    /// -- TODO merge docs possibly move to AppendOptions
     ///
     /// Pass a date in order to set the date that the message was originally sent.
     ///
     /// > If a date-time is specified, the internal date SHOULD be set in
     /// > the resulting message; otherwise, the internal date of the
     /// > resulting message is set to the current date and time by default.
-    pub fn append_with_flags_and_date<S: AsRef<str>, B: AsRef<[u8]>>(
+    pub fn append<'a, S: AsRef<str>, B: AsRef<[u8]>>(
         &mut self,
         mailbox: S,
         content: B,
-        flags: &[Flag<'_>],
-        date: impl Into<Option<DateTime<FixedOffset>>>,
+        options: impl Into<Option<AppendOptions<'a>>>,
     ) -> Result<()> {
         let content = content.as_ref();
-        let flagstr = flags
+        let options_ = options.into().unwrap_or(AppendOptions::default());
+
+        let flagstr = options_
+            .flags
+            .unwrap_or(&[])
             .iter()
             .filter(|f| **f != Flag::Recent)
             .map(|f| f.to_string())
             .collect::<Vec<String>>()
             .join(" ");
-        let datestr = match date.into() {
-            Some(date) => format!(" \"{}\"", date.format("%d-%h-%Y %T %z")),
-            None => "".to_string(),
+
+        let datestr = if let Some(date) = options_.date {
+            format!(" \"{}\"", date.format("%d-%h-%Y %T %z"))
+        } else {
+            "".to_string()
         };
 
         self.run_command(&format!(
diff --git a/tests/imap_integration.rs b/tests/imap_integration.rs
index b37f3f3..18dd3e8 100644
--- a/tests/imap_integration.rs
+++ b/tests/imap_integration.rs
@@ -253,7 +253,8 @@ fn append() {
     let mbox = "INBOX";
     c.select(mbox).unwrap();
     //append
-    c.append(mbox, e.message_to_string().unwrap()).unwrap();
+    c.append(mbox, e.message_to_string().unwrap(), None)
+        .unwrap();
 
     // now we should see the e-mail!
     let inbox = c.uid_search("ALL").unwrap();
@@ -301,8 +302,15 @@ fn append_with_flags() {
     c.select(mbox).unwrap();
     //append
     let flags: &[Flag] = &[Flag::Seen, Flag::Flagged];
-    c.append_with_flags(mbox, e.message_to_string().unwrap(), flags)
-        .unwrap();
+    c.append(
+        mbox,
+        e.message_to_string().unwrap(),
+        imap::AppendOptions {
+            flags: Some(flags),
+            date: None,
+        },
+    )
+    .unwrap();
 
     // now we should see the e-mail!
     let inbox = c.uid_search("ALL").unwrap();
@@ -358,8 +366,15 @@ fn append_with_flags_and_date() {
     let date = FixedOffset::east(8 * 3600)
         .ymd(2020, 12, 13)
         .and_hms(13, 36, 36);
-    c.append_with_flags_and_date(mbox, e.message_to_string().unwrap(), flags, Some(date))
-        .unwrap();
+    c.append(
+        mbox,
+        e.message_to_string().unwrap(),
+        imap::AppendOptions {
+            flags: Some(flags),
+            date: Some(date),
+        },
+    )
+    .unwrap();
 
     // now we should see the e-mail!
     let inbox = c.uid_search("ALL").unwrap();

From 24445c5c652b6098d8c859411da74264105506dc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Thu, 17 Dec 2020 00:41:26 +0800
Subject: [PATCH 08/21] feat: add AppendCmd builder

---
 src/client.rs | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/src/client.rs b/src/client.rs
index 167ea70..1e33ab5 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -93,6 +93,41 @@ pub struct AppendOptions<'a> {
     pub date: Option<DateTime<FixedOffset>>,
 }
 
+/// A builder for the append command
+#[derive(Default)]
+pub struct AppendCmd<'a> {
+    flags: Vec<&'a Flag<'a>>,
+    date: Option<DateTime<FixedOffset>>,
+}
+
+impl<'a> AppendCmd<'a> {
+    /// Create a new AppendCmd builder
+    pub fn create() -> Self {
+        Self::default()
+    }
+
+    /// Append a flag
+    pub fn flag(&mut self, flag: &'a Flag<'a>) -> &mut Self {
+        self.flags.push(flag);
+        self
+    }
+
+    /// Set the internal date
+    pub fn internal_date(&mut self, date: DateTime<FixedOffset>) -> &mut Self {
+        self.date = Some(date);
+        self
+    }
+}
+
+impl<'a> Into<AppendOptions<'a>> for AppendCmd<'a> {
+    fn into(self) -> AppendOptions<'a> {
+        AppendOptions {
+            flags: Some(&self.flags[..]),
+            date: self.date,
+        }
+    }
+}
+
 // `Deref` instances are so we can make use of the same underlying primitives in `Client` and
 // `Session`
 impl<T: Read + Write> Deref for Client<T> {

From cdf320fb0c87009bd3856220d263b62180637b8c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Thu, 17 Dec 2020 11:02:48 +0800
Subject: [PATCH 09/21] refactor: use AppendCmd instead of AppendOptions

---
 src/client.rs             | 102 ++++++++++++++++----------------------
 tests/imap_integration.rs |  32 +++++-------
 2 files changed, 57 insertions(+), 77 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index 1e33ab5..6bbe119 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -84,28 +84,16 @@ pub struct Connection<T: Read + Write> {
     pub greeting_read: bool,
 }
 
-/// A set of options for the append command
-#[derive(Default)]
-pub struct AppendOptions<'a> {
-    /// Optional list of flags
-    pub flags: Option<&'a [Flag<'a>]>,
-    /// Optional internal date
-    pub date: Option<DateTime<FixedOffset>>,
-}
-
 /// A builder for the append command
-#[derive(Default)]
-pub struct AppendCmd<'a> {
+pub struct AppendCmd<'a, T: Read + Write> {
+    session: &'a Session<T>,
+    content: &'a [u8],
+    mailbox: &'a str,
     flags: Vec<&'a Flag<'a>>,
     date: Option<DateTime<FixedOffset>>,
 }
 
-impl<'a> AppendCmd<'a> {
-    /// Create a new AppendCmd builder
-    pub fn create() -> Self {
-        Self::default()
-    }
-
+impl<'a, T: Read + Write> AppendCmd<'a, T> {
     /// Append a flag
     pub fn flag(&mut self, flag: &'a Flag<'a>) -> &mut Self {
         self.flags.push(flag);
@@ -117,14 +105,40 @@ impl<'a> AppendCmd<'a> {
         self.date = Some(date);
         self
     }
-}
 
-impl<'a> Into<AppendOptions<'a>> for AppendCmd<'a> {
-    fn into(self) -> AppendOptions<'a> {
-        AppendOptions {
-            flags: Some(&self.flags[..]),
-            date: self.date,
+    /// Run command when set up
+    #[must_use]
+    pub fn run(&self) -> Result<()> {
+        let flagstr = self
+            .flags
+            .into_iter()
+            .filter(|f| **f != Flag::Recent)
+            .map(|f| f.to_string())
+            .collect::<Vec<String>>()
+            .join(" ");
+
+        let datestr = if let Some(date) = self.date {
+            format!(" \"{}\"", date.format("%d-%h-%Y %T %z"))
+        } else {
+            "".to_string()
+        };
+
+        self.session.run_command(&format!(
+            "APPEND \"{}\" ({}){} {{{}}}",
+            self.mailbox,
+            flagstr,
+            datestr,
+            self.content.len()
+        ))?;
+        let mut v = Vec::new();
+        self.session.readline(&mut v)?;
+        if !v.starts_with(b"+") {
+            return Err(Error::Append);
         }
+        self.session.stream.write_all(self.content)?;
+        self.session.stream.write_all(b"\r\n")?;
+        self.session.stream.flush()?;
+        self.session.read_response().map(|_| ())
     }
 }
 
@@ -1147,42 +1161,14 @@ impl<T: Read + Write> Session<T> {
         &mut self,
         mailbox: S,
         content: B,
-        options: impl Into<Option<AppendOptions<'a>>>,
-    ) -> Result<()> {
-        let content = content.as_ref();
-        let options_ = options.into().unwrap_or(AppendOptions::default());
-
-        let flagstr = options_
-            .flags
-            .unwrap_or(&[])
-            .iter()
-            .filter(|f| **f != Flag::Recent)
-            .map(|f| f.to_string())
-            .collect::<Vec<String>>()
-            .join(" ");
-
-        let datestr = if let Some(date) = options_.date {
-            format!(" \"{}\"", date.format("%d-%h-%Y %T %z"))
-        } else {
-            "".to_string()
-        };
-
-        self.run_command(&format!(
-            "APPEND \"{}\" ({}){} {{{}}}",
-            mailbox.as_ref(),
-            flagstr,
-            datestr,
-            content.len()
-        ))?;
-        let mut v = Vec::new();
-        self.readline(&mut v)?;
-        if !v.starts_with(b"+") {
-            return Err(Error::Append);
+    ) -> AppendCmd<'a, T> {
+        AppendCmd {
+            session: &self,
+            content: content.as_ref(),
+            mailbox: mailbox.as_ref(),
+            flags: Vec::new(),
+            date: None,
         }
-        self.stream.write_all(content)?;
-        self.stream.write_all(b"\r\n")?;
-        self.stream.flush()?;
-        self.read_response().map(|_| ())
     }
 
     /// The [`SEARCH` command](https://tools.ietf.org/html/rfc3501#section-6.4.4) searches the
diff --git a/tests/imap_integration.rs b/tests/imap_integration.rs
index 18dd3e8..abecb0f 100644
--- a/tests/imap_integration.rs
+++ b/tests/imap_integration.rs
@@ -253,7 +253,8 @@ fn append() {
     let mbox = "INBOX";
     c.select(mbox).unwrap();
     //append
-    c.append(mbox, e.message_to_string().unwrap(), None)
+    c.append(mbox, e.message_to_string().unwrap())
+        .run()
         .unwrap();
 
     // now we should see the e-mail!
@@ -302,15 +303,11 @@ fn append_with_flags() {
     c.select(mbox).unwrap();
     //append
     let flags: &[Flag] = &[Flag::Seen, Flag::Flagged];
-    c.append(
-        mbox,
-        e.message_to_string().unwrap(),
-        imap::AppendOptions {
-            flags: Some(flags),
-            date: None,
-        },
-    )
-    .unwrap();
+    c.append(mbox, e.message_to_string().unwrap())
+        .flag(Flag::Seen)
+        .flag(Flag::Flagged)
+        .run()
+        .unwrap();
 
     // now we should see the e-mail!
     let inbox = c.uid_search("ALL").unwrap();
@@ -366,15 +363,12 @@ fn append_with_flags_and_date() {
     let date = FixedOffset::east(8 * 3600)
         .ymd(2020, 12, 13)
         .and_hms(13, 36, 36);
-    c.append(
-        mbox,
-        e.message_to_string().unwrap(),
-        imap::AppendOptions {
-            flags: Some(flags),
-            date: Some(date),
-        },
-    )
-    .unwrap();
+    c.append(mbox, e.message_to_string().unwrap())
+        .flag(Flag::Seen)
+        .flag(Flag::Flagged)
+        .internal_date(date)
+        .run()
+        .unwrap();
 
     // now we should see the e-mail!
     let inbox = c.uid_search("ALL").unwrap();

From e6341ccfc0af9e617f15b1f59545ad3312bbe599 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Thu, 17 Dec 2020 11:37:01 +0800
Subject: [PATCH 10/21] fix: pass session as &mut

---
 src/client.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index 6bbe119..c5cfc82 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -86,7 +86,7 @@ pub struct Connection<T: Read + Write> {
 
 /// A builder for the append command
 pub struct AppendCmd<'a, T: Read + Write> {
-    session: &'a Session<T>,
+    session: &'a mut Session<T>,
     content: &'a [u8],
     mailbox: &'a str,
     flags: Vec<&'a Flag<'a>>,
@@ -1163,7 +1163,7 @@ impl<T: Read + Write> Session<T> {
         content: B,
     ) -> AppendCmd<'a, T> {
         AppendCmd {
-            session: &self,
+            session: self,
             content: content.as_ref(),
             mailbox: mailbox.as_ref(),
             flags: Vec::new(),

From b7bc84297979b7ad3f48e33300a149b406e8fb2a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Sun, 20 Dec 2020 13:03:54 +0800
Subject: [PATCH 11/21] fix: correct lifetimes and types for append

---
 src/client.rs             | 19 ++++++++-----------
 tests/imap_integration.rs |  7 +++----
 2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index c5cfc82..4fc4c25 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -89,13 +89,13 @@ pub struct AppendCmd<'a, T: Read + Write> {
     session: &'a mut Session<T>,
     content: &'a [u8],
     mailbox: &'a str,
-    flags: Vec<&'a Flag<'a>>,
+    flags: Vec<Flag<'a>>,
     date: Option<DateTime<FixedOffset>>,
 }
 
 impl<'a, T: Read + Write> AppendCmd<'a, T> {
     /// Append a flag
-    pub fn flag(&mut self, flag: &'a Flag<'a>) -> &mut Self {
+    pub fn flag(&mut self, flag: Flag<'a>) -> &mut Self {
         self.flags.push(flag);
         self
     }
@@ -108,11 +108,12 @@ impl<'a, T: Read + Write> AppendCmd<'a, T> {
 
     /// Run command when set up
     #[must_use]
-    pub fn run(&self) -> Result<()> {
+    pub fn run(&mut self) -> Result<()> {
         let flagstr = self
             .flags
+            .clone()
             .into_iter()
-            .filter(|f| **f != Flag::Recent)
+            .filter(|f| *f != Flag::Recent)
             .map(|f| f.to_string())
             .collect::<Vec<String>>()
             .join(" ");
@@ -1157,15 +1158,11 @@ impl<T: Read + Write> Session<T> {
     /// > If a date-time is specified, the internal date SHOULD be set in
     /// > the resulting message; otherwise, the internal date of the
     /// > resulting message is set to the current date and time by default.
-    pub fn append<'a, S: AsRef<str>, B: AsRef<[u8]>>(
-        &mut self,
-        mailbox: S,
-        content: B,
-    ) -> AppendCmd<'a, T> {
+    pub fn append<'a>(&'a mut self, mailbox: &'a str, content: &'a [u8]) -> AppendCmd<'a, T> {
         AppendCmd {
             session: self,
-            content: content.as_ref(),
-            mailbox: mailbox.as_ref(),
+            content,
+            mailbox,
             flags: Vec::new(),
             date: None,
         }
diff --git a/tests/imap_integration.rs b/tests/imap_integration.rs
index abecb0f..b32a0c0 100644
--- a/tests/imap_integration.rs
+++ b/tests/imap_integration.rs
@@ -253,7 +253,7 @@ fn append() {
     let mbox = "INBOX";
     c.select(mbox).unwrap();
     //append
-    c.append(mbox, e.message_to_string().unwrap())
+    c.append(mbox, e.message_to_string().unwrap().as_bytes())
         .run()
         .unwrap();
 
@@ -303,7 +303,7 @@ fn append_with_flags() {
     c.select(mbox).unwrap();
     //append
     let flags: &[Flag] = &[Flag::Seen, Flag::Flagged];
-    c.append(mbox, e.message_to_string().unwrap())
+    c.append(mbox, e.message_to_string().unwrap().as_bytes())
         .flag(Flag::Seen)
         .flag(Flag::Flagged)
         .run()
@@ -359,11 +359,10 @@ fn append_with_flags_and_date() {
     let mbox = "INBOX";
     c.select(mbox).unwrap();
     // append
-    let flags: &[Flag] = &[Flag::Seen, Flag::Flagged];
     let date = FixedOffset::east(8 * 3600)
         .ymd(2020, 12, 13)
         .and_hms(13, 36, 36);
-    c.append(mbox, e.message_to_string().unwrap())
+    c.append(mbox, e.message_to_string().unwrap().as_bytes())
         .flag(Flag::Seen)
         .flag(Flag::Flagged)
         .internal_date(date)

From 5053cfbb3ec2037e0cc59684e24d31499759f1c4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Sun, 20 Dec 2020 13:04:31 +0800
Subject: [PATCH 12/21] feat: add 'flags' method to add multiple flags at once

---
 src/client.rs             | 6 ++++++
 tests/imap_integration.rs | 3 +--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index 4fc4c25..74127ef 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -100,6 +100,12 @@ impl<'a, T: Read + Write> AppendCmd<'a, T> {
         self
     }
 
+    /// Append an array of flags
+    pub fn flags(&mut self, flags: &'a [Flag<'a>]) -> &mut Self {
+        self.flags.append(&mut flags.to_vec());
+        self
+    }
+
     /// Set the internal date
     pub fn internal_date(&mut self, date: DateTime<FixedOffset>) -> &mut Self {
         self.date = Some(date);
diff --git a/tests/imap_integration.rs b/tests/imap_integration.rs
index b32a0c0..536efd2 100644
--- a/tests/imap_integration.rs
+++ b/tests/imap_integration.rs
@@ -304,8 +304,7 @@ fn append_with_flags() {
     //append
     let flags: &[Flag] = &[Flag::Seen, Flag::Flagged];
     c.append(mbox, e.message_to_string().unwrap().as_bytes())
-        .flag(Flag::Seen)
-        .flag(Flag::Flagged)
+        .flags(flags)
         .run()
         .unwrap();
 

From 74ef623fc589bc20ce1773f1ab9ef4729fe6729d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Sun, 20 Dec 2020 13:09:57 +0800
Subject: [PATCH 13/21] docs: move flag + date documentation to AppendCmd

---
 src/client.rs | 41 +++++++++++++++++------------------------
 1 file changed, 17 insertions(+), 24 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index 74127ef..aa5623f 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -94,7 +94,16 @@ pub struct AppendCmd<'a, T: Read + Write> {
 }
 
 impl<'a, T: Read + Write> AppendCmd<'a, T> {
-    /// Append a flag
+    /// The [`APPEND` command](https://tools.ietf.org/html/rfc3501#section-6.3.11) can take
+    /// an optional FLAGS parameter to set the flags on the new message.
+    ///
+    /// > If a flag parenthesized list is specified, the flags SHOULD be set
+    /// > in the resulting message; otherwise, the flag list of the
+    /// > resulting message is set to empty by default.  In either case, the
+    /// > Recent flag is also set.
+    ///
+    /// The [`\Recent` flag](https://tools.ietf.org/html/rfc3501#section-2.3.2) is not
+    /// allowed as an argument to `APPEND` and will be filtered out if present in `flags`.
     pub fn flag(&mut self, flag: Flag<'a>) -> &mut Self {
         self.flags.push(flag);
         self
@@ -106,14 +115,18 @@ impl<'a, T: Read + Write> AppendCmd<'a, T> {
         self
     }
 
-    /// Set the internal date
+    /// Pass a date in order to set the date that the message was originally sent.
+    ///
+    /// > If a date-time is specified, the internal date SHOULD be set in
+    /// > the resulting message; otherwise, the internal date of the
+    /// > resulting message is set to the current date and time by default.
     pub fn internal_date(&mut self, date: DateTime<FixedOffset>) -> &mut Self {
         self.date = Some(date);
         self
     }
 
-    /// Run command when set up
-    #[must_use]
+    /// Run command
+    #[must_use = "always run a command once options are configured"]
     pub fn run(&mut self) -> Result<()> {
         let flagstr = self
             .flags
@@ -1144,26 +1157,6 @@ impl<T: Read + Write> Session<T> {
     /// `EXISTS` response.  If the server does not do so, the client MAY issue a `NOOP` command (or
     /// failing that, a `CHECK` command) after one or more `APPEND` commands.
     ///
-    /// -- TODO merge docs possibly move to AppendOptions
-    ///
-    /// The [`APPEND` command](https://tools.ietf.org/html/rfc3501#section-6.3.11) can take
-    /// an optional FLAGS parameter to set the flags on the new message.
-    ///
-    /// > If a flag parenthesized list is specified, the flags SHOULD be set
-    /// > in the resulting message; otherwise, the flag list of the
-    /// > resulting message is set to empty by default.  In either case, the
-    /// > Recent flag is also set.
-    ///
-    /// The [`\Recent` flag](https://tools.ietf.org/html/rfc3501#section-2.3.2) is not
-    /// allowed as an argument to `APPEND` and will be filtered out if present in `flags`.
-    ///
-    /// -- TODO merge docs possibly move to AppendOptions
-    ///
-    /// Pass a date in order to set the date that the message was originally sent.
-    ///
-    /// > If a date-time is specified, the internal date SHOULD be set in
-    /// > the resulting message; otherwise, the internal date of the
-    /// > resulting message is set to the current date and time by default.
     pub fn append<'a>(&'a mut self, mailbox: &'a str, content: &'a [u8]) -> AppendCmd<'a, T> {
         AppendCmd {
             session: self,

From 19af971c9a435bcb4f9d389b0deb33ac1d62249c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?=
 <mblarsen@users.noreply.github.com>
Date: Mon, 21 Dec 2020 10:37:18 +0800
Subject: [PATCH 14/21] refactor: use extend instead of append

Co-authored-by: Jon Gjengset <jon@thesquareplanet.com>
---
 src/client.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index aa5623f..e7833e4 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -110,8 +110,8 @@ impl<'a, T: Read + Write> AppendCmd<'a, T> {
     }
 
     /// Append an array of flags
-    pub fn flags(&mut self, flags: &'a [Flag<'a>]) -> &mut Self {
-        self.flags.append(&mut flags.to_vec());
+    pub fn flags(&mut self, flags: impl IntoIterator<Item = Flag<'a>>) -> &mut Self {
+        self.flags.extend(flags);
         self
     }
 

From 029da6fd5226c1aa607881a66907a8cfc4878325 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Mon, 21 Dec 2020 11:19:42 +0800
Subject: [PATCH 15/21] refactor: move must_use to AppendCmd

---
 src/client.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/client.rs b/src/client.rs
index e7833e4..5d4ddd4 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -85,6 +85,7 @@ pub struct Connection<T: Read + Write> {
 }
 
 /// A builder for the append command
+#[must_use]
 pub struct AppendCmd<'a, T: Read + Write> {
     session: &'a mut Session<T>,
     content: &'a [u8],
@@ -126,7 +127,6 @@ impl<'a, T: Read + Write> AppendCmd<'a, T> {
     }
 
     /// Run command
-    #[must_use = "always run a command once options are configured"]
     pub fn run(&mut self) -> Result<()> {
         let flagstr = self
             .flags

From 8cd8a210085e6d86ec3a3859b96dbcf149a9094f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Mon, 21 Dec 2020 11:21:22 +0800
Subject: [PATCH 16/21] refactor: rename run to finish

---
 src/client.rs             | 2 +-
 tests/imap_integration.rs | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index 5d4ddd4..8b94376 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -127,7 +127,7 @@ impl<'a, T: Read + Write> AppendCmd<'a, T> {
     }
 
     /// Run command
-    pub fn run(&mut self) -> Result<()> {
+    pub fn finish(&mut self) -> Result<()> {
         let flagstr = self
             .flags
             .clone()
diff --git a/tests/imap_integration.rs b/tests/imap_integration.rs
index 536efd2..9d443cd 100644
--- a/tests/imap_integration.rs
+++ b/tests/imap_integration.rs
@@ -254,7 +254,7 @@ fn append() {
     c.select(mbox).unwrap();
     //append
     c.append(mbox, e.message_to_string().unwrap().as_bytes())
-        .run()
+        .finish()
         .unwrap();
 
     // now we should see the e-mail!
@@ -305,7 +305,7 @@ fn append_with_flags() {
     let flags: &[Flag] = &[Flag::Seen, Flag::Flagged];
     c.append(mbox, e.message_to_string().unwrap().as_bytes())
         .flags(flags)
-        .run()
+        .finish()
         .unwrap();
 
     // now we should see the e-mail!
@@ -365,7 +365,7 @@ fn append_with_flags_and_date() {
         .flag(Flag::Seen)
         .flag(Flag::Flagged)
         .internal_date(date)
-        .run()
+        .finish()
         .unwrap();
 
     // now we should see the e-mail!

From b2f2e297c2f7d9cf04005bf5c0a76f923b1d4140 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Mon, 21 Dec 2020 11:21:40 +0800
Subject: [PATCH 17/21] docs: improve docs

---
 src/client.rs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/client.rs b/src/client.rs
index 8b94376..0637514 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -110,7 +110,7 @@ impl<'a, T: Read + Write> AppendCmd<'a, T> {
         self
     }
 
-    /// Append an array of flags
+    /// Set multiple flags at once.
     pub fn flags(&mut self, flags: impl IntoIterator<Item = Flag<'a>>) -> &mut Self {
         self.flags.extend(flags);
         self
@@ -126,7 +126,10 @@ impl<'a, T: Read + Write> AppendCmd<'a, T> {
         self
     }
 
-    /// Run command
+    /// Finishes up the command and executes it.
+    ///
+    /// Note: be sure to set flags and optional date before you
+    /// finish the command.
     pub fn finish(&mut self) -> Result<()> {
         let flagstr = self
             .flags

From 80f54b1e81e339e67bcebe1edc276402056b0679 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michael=20B=C3=B8cker-Larsen?= <m19n@pm.me>
Date: Tue, 22 Dec 2020 20:31:55 +0800
Subject: [PATCH 18/21] test: correct test for append_with_flags

---
 tests/imap_integration.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/imap_integration.rs b/tests/imap_integration.rs
index 9d443cd..997b2f5 100644
--- a/tests/imap_integration.rs
+++ b/tests/imap_integration.rs
@@ -302,7 +302,7 @@ fn append_with_flags() {
     let mbox = "INBOX";
     c.select(mbox).unwrap();
     //append
-    let flags: &[Flag] = &[Flag::Seen, Flag::Flagged];
+    let flags = vec![Flag::Seen, Flag::Flagged];
     c.append(mbox, e.message_to_string().unwrap().as_bytes())
         .flags(flags)
         .finish()

From 9b6ff70e3b387432c4ba3ab2ca1a84259df8e40b Mon Sep 17 00:00:00 2001
From: Milo Mirate <mmirate@users.noreply.github.com>
Date: Tue, 12 Jan 2021 23:30:38 -0500
Subject: [PATCH 19/21] Avoid trying to FETCH an empty set of messages (#177)

Also, apply correct validation to FETCH arguments.
---
 CHANGELOG.md  |   2 +
 src/client.rs | 107 ++++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 89 insertions(+), 20 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ebfdbe4..1df8120 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+ - Handle empty-set inputs to `fetch` and `uid_fetch` (#177)
+
 ### Removed
 
 ## [2.4.0] - 2020-12-15
diff --git a/src/client.rs b/src/client.rs
index 26a1432..2438a86 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -28,15 +28,74 @@ macro_rules! quote {
     };
 }
 
+trait OptionExt<E> {
+    fn err(self) -> std::result::Result<(), E>;
+}
+
+impl<E> OptionExt<E> for Option<E> {
+    fn err(self) -> std::result::Result<(), E> {
+        match self {
+            Some(e) => Err(e),
+            None => Ok(()),
+        }
+    }
+}
+
+/// Convert the input into what [the IMAP
+/// grammar](https://tools.ietf.org/html/rfc3501#section-9)
+/// calls "quoted", which is reachable from "string" et al.
+/// Also ensure it doesn't contain a colliding command-delimiter (newline).
 fn validate_str(value: &str) -> Result<String> {
-    let quoted = quote!(value);
-    if quoted.find('\n').is_some() {
-        return Err(Error::Validate(ValidateError('\n')));
-    }
-    if quoted.find('\r').is_some() {
-        return Err(Error::Validate(ValidateError('\r')));
-    }
-    Ok(quoted)
+    validate_str_noquote(value)?;
+    Ok(quote!(value))
+}
+
+/// Ensure the input doesn't contain a command-terminator (newline), but don't quote it like
+/// `validate_str`.
+/// This is helpful for things like the FETCH attributes, which,
+/// per [the IMAP grammar](https://tools.ietf.org/html/rfc3501#section-9) may not be quoted:
+///
+/// > fetch     = "FETCH" SP sequence-set SP ("ALL" / "FULL" / "FAST" /
+/// >             fetch-att / "(" fetch-att *(SP fetch-att) ")")
+/// >
+/// > fetch-att = "ENVELOPE" / "FLAGS" / "INTERNALDATE" /
+/// >             "RFC822" [".HEADER" / ".SIZE" / ".TEXT"] /
+/// >             "BODY" ["STRUCTURE"] / "UID" /
+/// >             "BODY" section ["<" number "." nz-number ">"] /
+/// >             "BODY.PEEK" section ["<" number "." nz-number ">"]
+///
+/// Note the lack of reference to any of the string-like rules or the quote characters themselves.
+fn validate_str_noquote(value: &str) -> Result<&str> {
+    value
+        .matches(|c| c == '\n' || c == '\r')
+        .next()
+        .and_then(|s| s.chars().next())
+        .map(|offender| Error::Validate(ValidateError(offender)))
+        .err()?;
+    Ok(value)
+}
+
+/// This ensures the input doesn't contain a command-terminator or any other whitespace
+/// while leaving it not-quoted.
+/// This is needed because, per [the formal grammer given in RFC
+/// 3501](https://tools.ietf.org/html/rfc3501#section-9), a sequence set consists of the following:
+///
+/// > sequence-set = (seq-number / seq-range) *("," sequence-set)
+/// > seq-range = seq-number ":" seq-number
+/// > seq-number = nz-number / "*"
+/// > nz-number       = digit-nz *DIGIT
+/// > digit-nz        = %x31-39
+///
+/// Note the lack of reference to SP or any other such whitespace terminals.
+/// Per this grammar, in theory we ought to be even more restrictive than "no whitespace".
+fn validate_sequence_set(value: &str) -> Result<&str> {
+    value
+        .matches(|c: char| c.is_ascii_whitespace())
+        .next()
+        .and_then(|s| s.chars().next())
+        .map(|offender| Error::Validate(ValidateError(offender)))
+        .err()?;
+    Ok(value)
 }
 
 /// An authenticated IMAP session providing the usual IMAP commands. This type is what you get from
@@ -543,12 +602,16 @@ impl<T: Read + Write> Session<T> {
         S1: AsRef<str>,
         S2: AsRef<str>,
     {
-        self.run_command_and_read_response(&format!(
-            "FETCH {} {}",
-            sequence_set.as_ref(),
-            query.as_ref()
-        ))
-        .and_then(|lines| parse_fetches(lines, &mut self.unsolicited_responses_tx))
+        if sequence_set.as_ref().is_empty() {
+            parse_fetches(vec![], &mut self.unsolicited_responses_tx)
+        } else {
+            self.run_command_and_read_response(&format!(
+                "FETCH {} {}",
+                validate_sequence_set(sequence_set.as_ref())?,
+                validate_str_noquote(query.as_ref())?
+            ))
+            .and_then(|lines| parse_fetches(lines, &mut self.unsolicited_responses_tx))
+        }
     }
 
     /// Equivalent to [`Session::fetch`], except that all identifiers in `uid_set` are
@@ -558,12 +621,16 @@ impl<T: Read + Write> Session<T> {
         S1: AsRef<str>,
         S2: AsRef<str>,
     {
-        self.run_command_and_read_response(&format!(
-            "UID FETCH {} {}",
-            uid_set.as_ref(),
-            query.as_ref()
-        ))
-        .and_then(|lines| parse_fetches(lines, &mut self.unsolicited_responses_tx))
+        if uid_set.as_ref().is_empty() {
+            parse_fetches(vec![], &mut self.unsolicited_responses_tx)
+        } else {
+            self.run_command_and_read_response(&format!(
+                "UID FETCH {} {}",
+                validate_sequence_set(uid_set.as_ref())?,
+                validate_str_noquote(query.as_ref())?
+            ))
+            .and_then(|lines| parse_fetches(lines, &mut self.unsolicited_responses_tx))
+        }
     }
 
     /// Noop always succeeds, and it does nothing.

From bf9191527f5d5fe97a1de181123d4526558ccd51 Mon Sep 17 00:00:00 2001
From: Jon Gjengset <jon@thesquareplanet.com>
Date: Tue, 12 Jan 2021 20:32:23 -0800
Subject: [PATCH 20/21] Release 2.4.1

---
 CHANGELOG.md | 12 ++++++++----
 Cargo.toml   |  2 +-
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1df8120..27fbd5e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,10 +9,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
- - Handle empty-set inputs to `fetch` and `uid_fetch` (#177)
-
 ### Removed
 
+## [2.4.1] - 2021-01-12
+### Changed
+
+ - Handle empty-set inputs to `fetch` and `uid_fetch` (#177)
+
 ## [2.4.0] - 2020-12-15
 ### Added
 
@@ -36,7 +39,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  - MSRV increased
  - Better documentation of server greeting handling (#168)
 
-[Unreleased]: https://github.com/jonhoo/rust-imap/compare/v2.4.0...HEAD
-[2.4.0]: https://github.com/jonhoo/rust-imap/compare/v2.2.0...v2.4.0
+[Unreleased]: https://github.com/jonhoo/rust-imap/compare/v2.4.1...HEAD
+[2.4.1]: https://github.com/jonhoo/rust-imap/compare/v2.4.0...v2.4.1
+[2.4.0]: https://github.com/jonhoo/rust-imap/compare/v2.3.0...v2.4.0
 [2.3.0]: https://github.com/jonhoo/rust-imap/compare/v2.2.0...v2.3.0
 [2.2.0]: https://github.com/jonhoo/rust-imap/compare/v2.1.2...v2.2.0
diff --git a/Cargo.toml b/Cargo.toml
index 1dd1d68..f56fb92 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "imap"
-version = "2.4.0"
+version = "2.4.1"
 authors = ["Matt McCoy <mattnenterprise@yahoo.com>",
            "Jon Gjengset <jon@thesquareplanet.com>"]
 documentation = "https://docs.rs/imap/"

From 7e2ab19409156411ee77b788ac76f0975f052a87 Mon Sep 17 00:00:00 2001
From: Jon Gjengset <jon@thesquareplanet.com>
Date: Sat, 6 Mar 2021 09:36:43 -0800
Subject: [PATCH 21/21] Prepare for 3.0.0 alpha

---
 Cargo.toml | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index f56fb92..05ad84b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,26 +1,18 @@
 [package]
 name = "imap"
-version = "2.4.1"
-authors = ["Matt McCoy <mattnenterprise@yahoo.com>",
-           "Jon Gjengset <jon@thesquareplanet.com>"]
+version = "3.0.0-alpha.1"
+authors = ["Jon Gjengset <jon@thesquareplanet.com>",
+           "Matt McCoy <mattnenterprise@yahoo.com>"]
 documentation = "https://docs.rs/imap/"
 repository = "https://github.com/jonhoo/rust-imap"
 homepage = "https://github.com/jonhoo/rust-imap"
 description = "IMAP client for Rust"
-readme = "README.md"
-license = "Apache-2.0/MIT"
+license = "Apache-2.0 OR MIT"
 edition = "2018"
 
 keywords = ["email", "imap"]
 categories = ["email", "network-programming"]
 
-[badges]
-azure-devops = { project = "jonhoo/jonhoo", pipeline = "imap", build = "11" }
-codecov = { repository = "jonhoo/rust-imap", branch = "master", service = "github" }
-maintenance = { status = "actively-developed" }
-is-it-maintained-issue-resolution = { repository = "jonhoo/rust-imap" }
-is-it-maintained-open-issues = { repository = "jonhoo/rust-imap" }
-
 [features]
 tls = ["native-tls"]
 default = ["tls"]