mail-parser

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mail-parser is an e-mail parsing library written in Rust that fully conforms to the Internet Message Format standard (RFC 5322), the Multipurpose Internet Mail Extensions (MIME; RFC 2045 - 2049) as well as many other internet messaging RFCs.

It also supports decoding messages in 41 different character sets including obsolete formats such as UTF-7. All Unicode (UTF-*) and single-byte character sets are handled internally by the library while support for legacy multi-byte encodings of Chinese and Japanese languages such as BIG5 or ISO-2022-JP is provided by the optional dependency encoding_rs.

In general, this library abides by the Postel's law or Robustness Principle which states that an implementation must be conservative in its sending behavior and liberal in its receiving behavior. This means that mail-parser will make a best effort to parse non-conformant e-mail messages as long as these do not deviate too much from the standard.

Unlike other e-mail parsing libraries that return nested representations of the different MIME parts in a message, this library conforms to RFC 8621, Section 4.1.4 and provides a more human-friendly representation of the message contents consisting of just text body parts, html body parts and attachments. Additionally, conversion to/from HTML and plain text inline body parts is done automatically when the alternative version is missing.

Performance and memory safety were two important factors while designing mail-parser:

Usage Example

```rust let input = br#"From: Art Vandelay art@vandelay.com (Vandelay Industries) To: "Colleagues": "James Smythe" james@vandelay.com; Friends: jane@example.com, =?UTF-8?Q?John_Sm=C3=AEth?= john@example.com; Date: Sat, 20 Nov 2021 14:22:01 -0800 Subject: Why not both importing AND exporting? =?utf-8?b?4pi6?= Content-Type: multipart/mixed; boundary="festivus";

--festivus Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: base64

PGh0bWw+PHA+SSB3YXMgdGhpbmtpbmcgYWJvdXQgcXVpdHRpbmcgdGhlICZsZHF1bztle HBvcnRpbmcmcmRxdW87IHRvIGZvY3VzIGp1c3Qgb24gdGhlICZsZHF1bztpbXBvcnRpbm cmcmRxdW87LDwvcD48cD5idXQgdGhlbiBJIHRob3VnaHQsIHdoeSBub3QgZG8gYm90aD8 gJiN4MjYzQTs8L3A+PC9odG1sPg== --festivus Content-Type: message/rfc822

From: "Cosmo Kramer" kramer@kramerica.com Subject: Exporting my book about coffee tables Content-Type: multipart/mixed; boundary="giddyup";

--giddyup Content-Type: text/plain; charset="utf-16" Content-Transfer-Encoding: quoted-printable

=FF=FE=0C!5=D8"=DD5=D8)=DD5=D8-=DD =005=D8=DD5=D8"=DD =005=D8"= =DD5=D85=DD5=D8-=DD5=D8,=DD5=D8/=DD5=D81=DD =005=D8=DD5=D86=DD = =005=D8=1F=DD5=D8,=DD5=D8,=DD5=D8(=DD =005=D8-=DD5=D8)=DD5=D8"= =DD5=D8=1E=DD5=D80=DD5=D8"=DD!=00 --giddyup Content-Type: image/gif; name1="about "; name0="Book "; name2=utf-8''%e2%98%95 tables.gif Content-Transfer-Encoding: Base64 Content-Disposition: attachment

R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 --giddyup-- --festivus-- "#;

let message = Message::parse(input).unwrap();

// Parses addresses (including comments), lists and groups
assert_eq!(
    message.get_from(),
    &HeaderValue::Address(Addr::new(
        "Art Vandelay (Vandelay Industries)".into(),
        "art@vandelay.com"
    ))
);

assert_eq!(
    message.get_to(),
    &HeaderValue::GroupList(vec![
        Group::new(
            "Colleagues",
            vec![Addr::new("James Smythe".into(), "james@vandelay.com")]
        ),
        Group::new(
            "Friends",
            vec![
                Addr::new(None, "jane@example.com"),
                Addr::new("John Smîth".into(), "john@example.com"),
            ]
        )
    ])
);

assert_eq!(
    message.get_date().unwrap().to_iso8601(),
    "2021-11-20T14:22:01-08:00"
);

// RFC2047 support for encoded text in message readers
assert_eq!(
    message.get_subject().unwrap(),
    "Why not both importing AND exporting? ☺"
);

// HTML and text body parts are returned conforming to RFC8621, Section 4.1.4
assert_eq!(
    message.get_html_body(0).unwrap(),
    concat!(
        "<html><p>I was thinking about quitting the &ldquo;exporting&rdquo; to ",
        "focus just on the &ldquo;importing&rdquo;,</p><p>but then I thought,",
        " why not do both? &#x263A;</p></html>"
    )
);

// HTML parts are converted to plain text (and viceversa) when missing
assert_eq!(
    message.get_text_body(0).unwrap(),
    concat!(
        "I was thinking about quitting the “exporting” to focus just on the",
        " “importing”,\nbut then I thought, why not do both? ☺\n"
    )
);

// Supports nested messages as well as multipart/digest
let nested_message = message
    .get_attachment(0)
    .unwrap()
    .unwrap_message();

assert_eq!(
    nested_message.get_subject().unwrap(),
    "Exporting my book about coffee tables"
);

// Handles UTF-* as well as many legacy encodings
assert_eq!(
    nested_message.get_text_body(0).unwrap(),
    "ℌ𝔢𝔩𝔭 𝔪𝔢 𝔢𝔵𝔭𝔬𝔯𝔱 𝔪𝔶 𝔟𝔬𝔬𝔨 𝔭𝔩𝔢𝔞𝔰𝔢!"
);
assert_eq!(
    nested_message.get_html_body(0).unwrap(),
    "<html><body>ℌ𝔢𝔩𝔭 𝔪𝔢 𝔢𝔵𝔭𝔬𝔯𝔱 𝔪𝔶 𝔟𝔬𝔬𝔨 𝔭𝔩𝔢𝔞𝔰𝔢!</body></html>"
);

let nested_attachment = nested_message.get_attachment(0).unwrap().unwrap_binary();

assert_eq!(nested_attachment.len(), 42);

// Full RFC2231 support for continuations and character sets
assert_eq!(
    nested_attachment.get_attachment_name().unwrap(),
    "Book about ☕ tables.gif"
);

// Integrates with Serde
println!("{}", serde_json::to_string_pretty(&message).unwrap());
println!("{}", serde_yaml::to_string(&message).unwrap());

```

More examples available under the examples directory. Please note that this library does not support building e-mail messages as this functionality is provided separately by the mail-builder crate.

Testing, Fuzzing & Benchmarking

To run the testsuite:

bash $ cargo test --all-features

or, to run the testsuite with MIRI:

bash $ cargo +nightly miri test --all-features

To fuzz the library with cargo-fuzz:

bash $ cargo +nightly fuzz run mail_parser

and, to run the benchmarks:

bash $ cargo +nightly bench --all-features

Conformed RFCs

Supported Character Sets

Supported character sets via the optional dependency encoding_rs:

License

Licensed under either of

at your option.

Copyright

Copyright (C) 2020-2022, Stalwart Labs, Minter Ltd.

See [COPYING] for the license.