rustmailer · gabeosx · Apr 20, 2026 · May 3, 2026 · May 5, 2026 · May 9, 2026
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
@@ -19,7 +19,7 @@ jobs:
 
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
@@ -28,45 +28,36 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: dtolnay/rust-toolchain@stable
         with:
           components: rustfmt, clippy
       - run: cargo fmt --all -- --check
       - run: cargo clippy --all-targets -- -D warnings
 
-  msrv-proto:
+  msrv:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: dtolnay/rust-toolchain@master
         with:
-          toolchain: 1.61.0
-      - run: cargo check --manifest-path imap-proto/Cargo.toml --lib --all-features
-
-  msrv-tokio:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v6
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: 1.71.0
-      - run: cargo check --manifest-path tokio-imap/Cargo.toml --lib --all-features
+          toolchain: 1.70.0
+      - run: cargo check --lib --all-features
 
   coverage:
     runs-on: ubuntu-latest
     environment: Coverage
     env:
       CARGO_TERM_COLOR: always
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: dtolnay/rust-toolchain@stable
       - name: Install cargo-llvm-cov
         uses: taiki-e/install-action@cargo-llvm-cov
       - name: Generate code coverage
-        run: cargo llvm-cov --all-features --workspace --lcov --output-path lcov.info
+        run: cargo llvm-cov --all-features --lcov --output-path lcov.info
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v6
+        uses: codecov/codecov-action@v7
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           files: lcov.info
@@ -75,5 +66,5 @@ jobs:
   audit:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: EmbarkStudios/cargo-deny-action@v2
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -0,0 +1,65 @@
+# Contributing
+
+Thanks for considering helping this project. There are many ways you can help: using the library
+and reporting bugs, reporting usability issues, making additions and improvements to the library,
+documentation and finding security bugs.
+
+## Reporting bugs
+
+Please file a GitHub issue. Include as much information as possible. Suspected protocol bugs are
+easier debugged with a pcap or reproduction steps.
+
+Feel free to file GitHub issues to get help, or ask a question.
+
+## AI policy
+
+Using AI (LLMs) as tools for coding is welcome. A high bar is held for all contributions to this
+project. Moreover, the project maintainers remain responsible for any code that is published as
+part of a release. Contributors are expected to be responsible for any code they publish.
+
+AI should not be used to generate comments when communicating with maintainers. Comments are
+expected to be written by humans. Comments that are believed to be written by AI may be hidden
+without notice.
+
+If you are opening an issue, you should be able to describe the problem in your own words.
+
+If you are opening a pull request, you are expected to be able to explain the proposed changes in
+your own words. This includes the pull request body and responses to questions. Make sure you have
+reviewed the PR yourself before submitting it for review to the maintainers. Do not copy responses
+from the AI when replying to questions from maintainers.
+
+If you wish to include context from an interaction with AI in your comments, it must be in a
+quote block (using `>`) and disclosed as such. It must be accompanied by human commentary
+explaining the relevance and implications of the context. Do not share long snippets.
+
+AI is useful when communicating as a non-native English speaker. If you are using AI to edit your
+comments for this purpose, please take the time to ensure it reflects your own voice and ideas.
+When using AI for translation, we recommend writing in your native language and including the AI
+translation in a quote block.
+
+## Code changes
+
+Some ideas and guidelines for contributions:
+
+- For large features, file an issue prior to starting work.
+  This means everyone can see what is in progress prior to a PR.
+- Feel free to submit a PR even if the work is not totally finished, for early feedback.
+- Prefer not to reference GitHub issue or PR numbers in commit messages.
+- Try to keep code formatting commits separate from functional commits.
+
+## Commit history
+
+We prefer to keep the commit history clean and easy to follow. As such, we prefer small commits
+that do one thing. In particular:
+
+* Avoid mixing refactoring and functional changes in the same commit if possible
+* Make mechanical changes (like renaming or moving code around) in a separate commit
+* Isolate updates to `Cargo.lock` in their own commits
+
+Our default workflow is to rebase clean commit history from a PR to `main`. As a result,
+we ask that review feedback is addressed in the originating commit rather than in new commits,
+by amending existing commits or squashing later commits back into the original commit(s).
+
+## Testing
+
+PRs which cause test failures or a significant coverage decrease are unlikely to be accepted.
diff --git a/Cargo.toml b/Cargo.toml
@@ -1,3 +1,18 @@
-[workspace]
-members = ["imap-proto", "tokio-imap"]
-resolver = "2"
+[package]
+name = "imap-proto"
+version = "0.17.0"
+edition = "2021"
+rust-version = "1.70"
+description = "IMAP protocol parser and data structures"
+documentation = "https://docs.rs/imap-proto"
+keywords = ["imap", "email"]
+categories = ["email", "network-programming", "parser-implementations"]
+repository = "https://github.com/djc/imap-proto"
+license = "MIT OR Apache-2.0"
+readme = "../README.md"
+
+[dependencies]
+nom = "7"
+
+[dev-dependencies]
+assert_matches = "1.3"
diff --git a/README.md b/README.md
@@ -1,73 +1,27 @@
-# imap-proto and tokio-imap
+# imap-proto
 
 [![Build status](https://github.com/djc/tokio-imap/workflows/CI/badge.svg)](https://github.com/djc/tokio-imap/actions?query=workflow%3ACI)
-[![Join the chat at https://gitter.im/djc/tokio-imap](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/djc/tokio-imap?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![crates.io, downloads](https://img.shields.io/crates/d/imap-proto.svg)](https://crates.io/crates/imap-proto)
+[![crates.io, latest release](https://img.shields.io/crates/v/imap-proto.svg)](https://crates.io/crates/imap-proto)
+[![API docs, latest release](https://docs.rs/imap-proto/badge.svg)](http://docs.rs/imap-proto)
+[![Chat](https://img.shields.io/discord/976380008299917365?logo=discord)](https://discord.gg/ujJ4pGzkGU)
 [![MIT license](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE-MIT)
 [![Apache License 2.0](https://img.shields.io/badge/license-ALv2-blue.svg)](./LICENSE-APACHE)
 
 All feedback welcome. Feel free to file bugs, requests for documentation and
-any other feedback to the [issue tracker][issues] or [tweet me][twitter].
+any other feedback to the [issue tracker][issues].
 
-tokio-imap and imap-proto are maintained by Dirkjan Ochtman. If you depend on these
+imap-proto was created and is maintained by Dirkjan Ochtman. If you depend on this
 projects, please support the project via [GitHub Sponsors] or contact me for support.
 
 [issues]: https://github.com/djc/tokio-imap/issues
-[twitter]: https://twitter.com/djco/
 [GitHub Sponsors]: https://github.com/sponsors/djc
 
-## tokio-imap: futures-based IMAP client
-
-[![crates.io, downloads](https://img.shields.io/crates/d/tokio-imap.svg)](https://crates.io/crates/tokio-imap)
-[![crates.io, latest release](https://img.shields.io/crates/v/tokio-imap.svg)](https://crates.io/crates/tokio-imap)
-[![API docs, latest release](https://docs.rs/tokio-imap/badge.svg)](http://docs.rs/tokio-imap)
-
-NOTE: Unlike imap-proto, tokio-imap doesn't receive much maintenance. As
-an alternative we suggest to evaluate async-imap instead.
-
-A [Tokio stack-based][Tokio_stack], fully asynchronous IMAP library, with strong focus on following
-the relevant specs, mainly [IMAP4rev1][rfc3501], but with limited support for
-the [Conditional STORE][rfc4551] extension. The type system is used to help
-enforce correctness where possible. So far, there is only client code and lots
-of infrastructure that supposedly could be shared -- no server yet. (If you
-want a tokio-based server, look at [IMAPServer][IMAPServer].)
-
-### Feature highlights
-
-* Fully asynchronous by using [tokio-core][tokio-core] and [tokio-io][tokio-io]
-* Uses the type system to help enforce correct operation according to spec
-* [nom][nom]-based parser (in imap-proto), so far only used for server response messages
-
-### Limitations
-
-* Alpha-level implementation -- no tests yet, limited protocol coverage
-* Server is totally unimplemented at this stage
-
-[rfc3501]: https://tools.ietf.org/html/rfc3501
-[rfc4551]: https://tools.ietf.org/html/rfc4551
-[IMAPServer]: https://github.com/Nordgedanken/IMAPServer-rs
-[docs]: https://docs.rs/tokio-imap
-[tokio-core]: https://github.com/tokio-rs/tokio-core
-[tokio-io]: https://github.com/tokio-rs/tokio-io
-[Tokio_stack]: https://tokio.rs
-[nom]: https://github.com/Geal/nom
-
-### How to get started
-
-Have a look at the [mailsync][mailsync] crate for example usage.
-
-[mailsync]: https://github.com/djc/mailsync
-
-## imap-proto: IMAP types and protocol parser
-
-[![crates.io, downloads](https://img.shields.io/crates/d/imap-proto.svg)](https://crates.io/crates/imap-proto)
-[![crates.io, latest release](https://img.shields.io/crates/v/imap-proto.svg)](https://crates.io/crates/imap-proto)
-[![API docs, latest release](https://docs.rs/imap-proto/badge.svg)](http://docs.rs/imap-proto)
+## Features
 
 imap-proto is a low-level IMAP protocol support crate, using the type system to
-provide a safe API. It was extracted from tokio-imap into a separate crate so that
-different protocol implementations can share it as common infrastructure
-(as proposed by [rust-imap][rust-imap] contributors).
-The code tries to closely follow the [IMAP4rev1 RFC][rfc3501], plus extensions.
+provide a safe API. The code tries to closely follow the [IMAP4rev1 RFC][rfc3501], plus
+several extensions.
 
 Protocol support is implemented in three parts:
 
@@ -76,18 +30,3 @@ Protocol support is implemented in three parts:
 * Builder types to help produce protocol messages
 
 [rfc3501]: https://tools.ietf.org/html/rfc3501
-[tokio-imap]: https://github.com/djc/tokio-imap
-[rust-imap]: https://github.com/mattnenterprise/rust-imap
-[issues]: https://github.com/djc/imap-proto/issues
-[twitter]: https://twitter.com/djco/
-
-### Progress
-
-- [ ] Client
-    - [ ] Parser: many common server responses implemented
-    - [ ] Types: most common types implemented
-    - [ ] Message builder: most common commands implemented
-- [ ] Server
-    - [ ] Parser: not started
-    - [ ] Types: not started
-    - [ ] Message builder: not started
diff --git a/deny.toml b/deny.toml
@@ -1,8 +1,3 @@
 [licenses]
-allow = ["Apache-2.0", "BSD-3-Clause", "CDLA-Permissive-2.0", "ISC", "MIT", "Unicode-3.0"]
+allow = ["Apache-2.0", "MIT"]
 private = { ignore = true }
-
-[[licenses.clarify]]
-name = "ring"
-expression = "ISC AND MIT AND OpenSSL"
-license-files = [{ path = "LICENSE", hash = 0xbd0eed23 }]
diff --git a/imap-proto/examples/parse_response.rs → examples/parse_response.rs b/imap-proto/examples/parse_response.rs → examples/parse_response.rs
diff --git a/imap-proto/fuzz/.gitignore → fuzz/.gitignore b/imap-proto/fuzz/.gitignore → fuzz/.gitignore
diff --git a/imap-proto/fuzz/Cargo.toml → fuzz/Cargo.toml b/imap-proto/fuzz/Cargo.toml → fuzz/Cargo.toml
diff --git a/.../fuzz/fuzz_targets/utf8_parse_response.rs → fuzz/fuzz_targets/utf8_parse_response.rs b/.../fuzz/fuzz_targets/utf8_parse_response.rs → fuzz/fuzz_targets/utf8_parse_response.rs
diff --git a/imap-proto/Cargo.toml b/imap-proto/Cargo.toml
diff --git a/imap-proto/src/builders/command.rs → src/builders/command.rs b/imap-proto/src/builders/command.rs → src/builders/command.rs
diff --git a/imap-proto/src/builders/mod.rs → src/builders/mod.rs b/imap-proto/src/builders/mod.rs → src/builders/mod.rs
diff --git a/imap-proto/src/lib.rs → src/lib.rs b/imap-proto/src/lib.rs → src/lib.rs
diff --git a/imap-proto/src/parser/bodystructure.rs → src/parser/bodystructure.rs b/imap-proto/src/parser/bodystructure.rs → src/parser/bodystructure.rs
diff --git a/imap-proto/src/parser/core.rs → src/parser/core.rs b/imap-proto/src/parser/core.rs → src/parser/core.rs
@@ -8,6 +8,7 @@ use nom::{
     IResult,
 };
 
+use std::borrow::Cow;
 use std::str::{from_utf8, FromStr};
 
 // ----- number -----
@@ -61,9 +62,17 @@ pub fn string(i: &[u8]) -> IResult<&[u8], &[u8]> {
     alt((quoted, literal))(i)
 }
 
-// string bytes as utf8
-pub fn string_utf8(i: &[u8]) -> IResult<&[u8], &str> {
-    map_res(string, from_utf8)(i)
+#[inline]
+fn lossy_str(bytes: &[u8]) -> Cow<'_, str> {
+    String::from_utf8_lossy(bytes)
+}
+
+// string bytes as utf8 — falls back to lossy decoding when the literal
+// or quoted contents include non-UTF-8 bytes (e.g. Latin-1 / ISO-8859-9
+// MIME filenames in BODYSTRUCTURE responses). Strict from_utf8 would
+// fail, breaking the entire response stream on a single bad mail.
+pub fn string_utf8(i: &[u8]) -> IResult<&[u8], Cow<'_, str>> {
+    map(string, lossy_str)(i)
 }
 
 // quoted = DQUOTE *QUOTED-CHAR DQUOTE
@@ -79,9 +88,9 @@ pub fn quoted(i: &[u8]) -> IResult<&[u8], &[u8]> {
     )(i)
 }
 
-// quoted bytes as utf8
-pub fn quoted_utf8(i: &[u8]) -> IResult<&[u8], &str> {
-    map_res(quoted, from_utf8)(i)
+// quoted bytes as utf8 — lossy, see comment on string_utf8.
+pub fn quoted_utf8(i: &[u8]) -> IResult<&[u8], Cow<'_, str>> {
+    map(quoted, lossy_str)(i)
 }
 
 // quoted-specials = DQUOTE / "\"
@@ -108,9 +117,9 @@ pub fn astring(i: &[u8]) -> IResult<&[u8], &[u8]> {
     alt((take_while1(is_astring_char), string))(i)
 }
 
-// astring bytes as utf8
-pub fn astring_utf8(i: &[u8]) -> IResult<&[u8], &str> {
-    map_res(astring, from_utf8)(i)
+// astring bytes as utf8 — lossy, see comment on string_utf8.
+pub fn astring_utf8(i: &[u8]) -> IResult<&[u8], Cow<'_, str>> {
+    map(astring, lossy_str)(i)
 }
 
 // ASTRING-CHAR = ATOM-CHAR / resp-specials
@@ -152,8 +161,8 @@ pub fn nstring(i: &[u8]) -> IResult<&[u8], Option<&[u8]>> {
     alt((map(nil, |_| None), map(string, Some)))(i)
 }
 
-// nstring bytes as utf8
-pub fn nstring_utf8(i: &[u8]) -> IResult<&[u8], Option<&str>> {
+// nstring bytes as utf8 — lossy, see comment on string_utf8.
+pub fn nstring_utf8(i: &[u8]) -> IResult<&[u8], Option<Cow<'_, str>>> {
     alt((map(nil, |_| None), map(string_utf8, Some)))(i)
 }
 
@@ -164,9 +173,9 @@ pub fn nil(i: &[u8]) -> IResult<&[u8], &[u8]> {
 
 // ----- text -----
 
-// text = 1*TEXT-CHAR
-pub fn text(i: &[u8]) -> IResult<&[u8], &str> {
-    map_res(take_while(is_text_char), from_utf8)(i)
+// text = 1*TEXT-CHAR — lossy, see comment on string_utf8.
+pub fn text(i: &[u8]) -> IResult<&[u8], Cow<'_, str>> {
+    map(take_while(is_text_char), lossy_str)(i)
 }
 
 // TEXT-CHAR = <any CHAR except CR and LF>
@@ -178,8 +187,17 @@ pub fn is_text_char(c: u8) -> bool {
 //          ; any 7-bit US-ASCII character,
 //          ;  excluding NUL
 // From RFC5234
+//
+// Real-world IMAP servers (Dovecot, Cyrus, …) regularly emit 8-bit bytes
+// inside quoted strings and literals — typically MIME filenames in
+// non-UTF-8 encodings like Latin-1 or ISO-8859-9 (Turkish). RFC 6855 /
+// IMAP4rev2 (RFC 9051) formally allow UTF-8 in these positions. Strict
+// 7-bit rejection breaks BODYSTRUCTURE parsing on a single bad mail and
+// desyncs the entire stream. Accept any non-NUL byte and let the
+// higher-level UTF-8 conversion deal with non-UTF-8 sequences via lossy
+// decoding.
 pub fn is_char(c: u8) -> bool {
-    matches!(c, 0x01..=0x7F)
+    c != 0
 }
 
 // ----- others -----