Email Message library for Rust

This project aims to provide a proper strongly typed way to build and parse emails.

Features

• Typed headers using hyperx::Header
• Support for headers with unicode values
• Support for MIME 1.0 multipart contents
• Streaming messages to save memory usage
• Email Address, Mailbox and Mailboxes types

Usage

Format email messages

With string body

The easiest way how we can create email message with simple string (see format_string.rs).

extern crate emailmessage;

use emailmessage::Message;

fn main() {
    let m: Message<&str> = Message::builder()
        .from("NoBody <nobody@domain.tld>".parse().unwrap())
        .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
        .to("Hei <hei@domain.tld>".parse().unwrap())
        .subject("Happy new year")
        .body("Be happy!");

    println!("{}", m);
}

Run this example:

$ cargo run --example format_string

From: NoBody <nobody@domain.tld>
Reply-To: Yuin <yuin@domain.tld>
To: Hei <hei@domain.tld>
Subject: Happy new year

Be happy!

The unicode header data will be encoded using UTF8-Base64 encoding.

With mime body

Single part

The more complex way is using MIME contents (see format_mime.rs).

extern crate emailmessage;

use emailmessage::{header, Message, SinglePart};

fn main() {
    let m: Message<SinglePart<&str>> = Message::builder()
        .from("NoBody <nobody@domain.tld>".parse().unwrap())
        .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
        .to("Hei <hei@domain.tld>".parse().unwrap())
        .subject("Happy new year")
        .mime_body(
            SinglePart::builder()
                .header(header::ContentType(
                    "text/plain; charset=utf8".parse().unwrap(),
                )).header(header::ContentTransferEncoding::QuotedPrintable)
                .body("Привет, мир!"),
        );

    println!("{}", m);
}

The body will be encoded using selected Content-Transfer-Encoding.

$ cargo run --example format_mime

From: NoBody <nobody@domain.tld>
Reply-To: Yuin <yuin@domain.tld>
To: Hei <hei@domain.tld>
Subject: Happy new year
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: quoted-printable

=D0=9F=D1=80=D0=B8=D0=B2=D0=B5=D1=82, =D0=BC=D0=B8=D1=80!

Multiple parts

And the more advanced way is a using multipart MIME contents (see format_multipart.rs).

extern crate emailmessage;
use emailmessage::{header, Message, MultiPart, SinglePart};
fn main() {
    let m: Message<MultiPart<&str>> = Message::builder()
        .from("NoBody <nobody@domain.tld>".parse().unwrap())
        .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
        .to("Hei <hei@domain.tld>".parse().unwrap())
        .subject("Happy new year")
        .mime_body(
            MultiPart::mixed()
            .multipart(
                MultiPart::alternative()
                .singlepart(
                    SinglePart::quoted_printable()
                    .header(header::ContentType("text/plain; charset=utf8".parse().unwrap()))
                    .body("Привет, мир!")
                )
                .multipart(
                    MultiPart::related()
                    .singlepart(
                        SinglePart::eight_bit()
                        .header(header::ContentType("text/html; charset=utf8".parse().unwrap()))
                        .body("<p><b>Hello</b>, <i>world</i>! <img src=smile.png></p>")
                    )
                    .singlepart(
                        SinglePart::base64()
                        .header(header::ContentType("image/png".parse().unwrap()))
                        .header(header::ContentDisposition {
                            disposition: header::DispositionType::Inline,
                            parameters: vec![],
                        })
                        .body("<smile-raw-image-data>")
                    )
                )
            )
            .singlepart(
                SinglePart::seven_bit()
                .header(header::ContentType("text/plain; charset=utf8".parse().unwrap()))
                .header(header::ContentDisposition {
                                 disposition: header::DispositionType::Attachment,
                                 parameters: vec![
                                     header::DispositionParam::Filename(
                                         header::Charset::Ext("utf-8".into()),
                                         None, "example.c".as_bytes().into()
                                     )
                                 ]
                             })
                .body("int main() { return 0; }")
            )
        );

    println!("{}", m);
}

$ cargo run --example format_multipart

From: NoBody <nobody@domain.tld>
Reply-To: Yuin <yuin@domain.tld>
To: Hei <hei@domain.tld>
Subject: Happy new year
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="RTxPCn9p31oAAAAAeQxtr1FbXr/i5vW1hFlH9oJqZRMWxRMK1QLjQ4OPqFk9R+0xUb/m"

--RTxPCn9p31oAAAAAeQxtr1FbXr/i5vW1hFlH9oJqZRMWxRMK1QLjQ4OPqFk9R+0xUb/m
Content-Type: multipart/alternative; boundary="qW9QCn9p31oAAAAAodFBg1L1Qrraa5hEl0bDJ6kfJMUcRT2LLSWEoeyhSEbUBIqbjWqy"

--qW9QCn9p31oAAAAAodFBg1L1Qrraa5hEl0bDJ6kfJMUcRT2LLSWEoeyhSEbUBIqbjWqy
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=utf8

=D0=9F=D1=80=D0=B8=D0=B2=D0=B5=D1=82, =D0=BC=D0=B8=D1=80!
--qW9QCn9p31oAAAAAodFBg1L1Qrraa5hEl0bDJ6kfJMUcRT2LLSWEoeyhSEbUBIqbjWqy
Content-Type: multipart/related; boundary="BV5RCn9p31oAAAAAUt42E9bYMDEAGCOWlxEz89Bv0qFA5Xsy6rOC3zRahMQ39IFZNnp8"

--BV5RCn9p31oAAAAAUt42E9bYMDEAGCOWlxEz89Bv0qFA5Xsy6rOC3zRahMQ39IFZNnp8
Content-Transfer-Encoding: 8bit
Content-Type: text/html; charset=utf8

<p><b>Hello</b>, <i>world</i>! <img src=smile.png></p>
--BV5RCn9p31oAAAAAUt42E9bYMDEAGCOWlxEz89Bv0qFA5Xsy6rOC3zRahMQ39IFZNnp8
Content-Transfer-Encoding: base64
Content-Type: image/png
Content-Disposition: inline

PHNtaWxlLXJhdy1pbWFnZS1kYXRhPg==
--BV5RCn9p31oAAAAAUt42E9bYMDEAGCOWlxEz89Bv0qFA5Xsy6rOC3zRahMQ39IFZNnp8--
--qW9QCn9p31oAAAAAodFBg1L1Qrraa5hEl0bDJ6kfJMUcRT2LLSWEoeyhSEbUBIqbjWqy--
--RTxPCn9p31oAAAAAeQxtr1FbXr/i5vW1hFlH9oJqZRMWxRMK1QLjQ4OPqFk9R+0xUb/m
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset=utf8
Content-Disposition: attachment; filename="example.c"

int main() { return 0; }
--RTxPCn9p31oAAAAAeQxtr1FbXr/i5vW1hFlH9oJqZRMWxRMK1QLjQ4OPqFk9R+0xUb/m--

Use streaming

The RAM-efficient way to formatting ans sending relatively big emails is a using streaming. For example, you would like to send server access logs in attachments, HTML-documents with related media resources or PDFs.

In examples above we actually allocated formatted emails in memory, but usually we don't want to do same for big emails which size measures in MBytes.

Simple string

The simple example below shows actually sent chunks of streamed message (see format_stream.rs).

extern crate emailmessage;
extern crate futures;
extern crate tokio;

use emailmessage::Message;
use futures::{Future, Stream};
use std::str::from_utf8;
use tokio::run;

fn main() {
    let m: Message = Message::builder()
        .from("NoBody <nobody@domain.tld>".parse().unwrap())
        .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
        .to("Hei <hei@domain.tld>".parse().unwrap())
        .subject("Happy new year")
        .body("Be happy!".into());

    let f = m
        .into_stream()
        .map(|chunk| {
            println!("CHUNK[[\n{}]]", from_utf8(&chunk).unwrap());
            chunk
        }).concat2()
        .map(|message| {
            println!("MESSAGE[[\n{}]]", from_utf8(&message).unwrap());
        }).map_err(|error| {
            eprintln!("ERROR: {}", error);
        });

    run(f);
}

$ cargo run --example format_stream

CHUNK[[
From: NoBody <nobody@domain.tld>
Reply-To: Yuin <yuin@domain.tld>
To: Hei <hei@domain.tld>
Subject: Happy new year
]]
CHUNK[[

Be happy!]]

In real world app we may do some buffering of stream to prevent too short and too long sendings.

Multipart data

(see format_stream_multipart.rs)

extern crate emailmessage;
extern crate futures;
extern crate tokio;
use emailmessage::{header, Message, MultiPart, SinglePart};
use futures::{Future, Stream};
use std::str::from_utf8;
use tokio::run;
fn main() {
    let b: MultiPart = MultiPart::mixed()
        .multipart(
            MultiPart::alternative()
                .singlepart(
                    SinglePart::quoted_printable()
                        .header(header::ContentType(
                            "text/plain; charset=utf8".parse().unwrap(),
                        )).body("Привет, мир!".into()),
                ).multipart(
                    MultiPart::related()
                        .singlepart(
                            SinglePart::eight_bit()
                                .header(header::ContentType(
                                    "text/html; charset=utf8".parse().unwrap(),
                                )).body(
                                    "<p><b>Hello</b>, <i>world</i>! <img src=smile.png></p>".into(),
                                ),
                        ).singlepart(
                            SinglePart::base64()
                                .header(header::ContentType("image/png".parse().unwrap()))
                                .header(header::ContentDisposition {
                                    disposition: header::DispositionType::Inline,
                                    parameters: vec![],
                                }).body("<smile-raw-image-data>".into()),
                        ),
                ),
        ).singlepart(
            SinglePart::seven_bit()
                .header(header::ContentType(
                    "text/plain; charset=utf8".parse().unwrap(),
                )).header(header::ContentDisposition {
                    disposition: header::DispositionType::Attachment,
                    parameters: vec![header::DispositionParam::Filename(
                        header::Charset::Ext("utf-8".into()),
                        None,
                        "example.c".as_bytes().into(),
                    )],
                }).body("int main() { return 0; }".into()),
        );

    let m = Message::builder()
        .from("NoBody <nobody@domain.tld>".parse().unwrap())
        .reply_to("Yuin <yuin@domain.tld>".parse().unwrap())
        .to("Hei <hei@domain.tld>".parse().unwrap())
        .subject("Happy new year")
        .mime_body(b.into_stream());

    let f = m
        .into_stream()
        .map(|chunk| {
            println!("CHUNK[[\n{}]]", from_utf8(&chunk).unwrap());
            chunk
        }).concat2()
        .map(|message| {
            println!("MESSSAGE[[\n{}]]", from_utf8(&message).unwrap());
        }).map_err(|error| {
            eprintln!("ERROR: {:?}", error);
        });

    run(f);
}

$ cargo run --example format_stream_multipart

CHUNK[[
From: NoBody <nobody@domain.tld>
Reply-To: Yuin <yuin@domain.tld>
To: Hei <hei@domain.tld>
Subject: Happy new year
MIME-Version: 1.0
]]
CHUNK[[
Content-Type: multipart/mixed; boundary="1S8dCMR/31oAAAAApHRNMETjK2uRsQs4mVVFKVNujcqnm8FHOXWvqARiaYy9ZmnpQ7uQ"
]]
CHUNK[[
--1S8dCMR/31oAAAAApHRNMETjK2uRsQs4mVVFKVNujcqnm8FHOXWvqARiaYy9ZmnpQ7uQ
]]
CHUNK[[
--1S8dCMR/31oAAAAApHRNMETjK2uRsQs4mVVFKVNujcqnm8FHOXWvqARiaYy9ZmnpQ7uQ
]]
CHUNK[[
Content-Type: multipart/alternative; boundary="TCMeCMR/31oAAAAAmf7KBuXt4qRk2RnBJCj8YJNdwm2dsadXxjOlC74hlb1tO6U/SqXY"
]]
CHUNK[[
--TCMeCMR/31oAAAAAmf7KBuXt4qRk2RnBJCj8YJNdwm2dsadXxjOlC74hlb1tO6U/SqXY
]]
CHUNK[[
--TCMeCMR/31oAAAAAmf7KBuXt4qRk2RnBJCj8YJNdwm2dsadXxjOlC74hlb1tO6U/SqXY
]]
CHUNK[[
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=utf8
]]
CHUNK[[
=D0=9F=D1=80=D0=B8=D0=B2=D0=B5=D1=82, =D0=BC=D0=B8=D1=80!]]
CHUNK[[
]]
CHUNK[[
--TCMeCMR/31oAAAAAmf7KBuXt4qRk2RnBJCj8YJNdwm2dsadXxjOlC74hlb1tO6U/SqXY
]]
CHUNK[[
Content-Type: multipart/related; boundary="YsgeCMR/31oAAAAAanzeyu/dFJGjfzDxpsAOLhRB0RfSw+DXefQybZxGq6HIBEzotZ5Y"
]]
CHUNK[[
--YsgeCMR/31oAAAAAanzeyu/dFJGjfzDxpsAOLhRB0RfSw+DXefQybZxGq6HIBEzotZ5Y
]]
CHUNK[[
--YsgeCMR/31oAAAAAanzeyu/dFJGjfzDxpsAOLhRB0RfSw+DXefQybZxGq6HIBEzotZ5Y
]]
CHUNK[[
Content-Transfer-Encoding: 8bit
Content-Type: text/html; charset=utf8
]]
CHUNK[[
<p><b>Hello</b>, <i>world</i>! <img src=smile.png></p>]]
CHUNK[[
]]
CHUNK[[
--YsgeCMR/31oAAAAAanzeyu/dFJGjfzDxpsAOLhRB0RfSw+DXefQybZxGq6HIBEzotZ5Y
]]
CHUNK[[
Content-Transfer-Encoding: base64
Content-Type: image/png
Content-Disposition: inline

]]
CHUNK[[
PHNtaWxlLXJhdy1pbWFnZS1kYXRhPg==]]
CHUNK[[

]]
CHUNK[[
--YsgeCMR/31oAAAAAanzeyu/dFJGjfzDxpsAOLhRB0RfSw+DXefQybZxGq6HIBEzotZ5Y--
]]
CHUNK[[
--TCMeCMR/31oAAAAAmf7KBuXt4qRk2RnBJCj8YJNdwm2dsadXxjOlC74hlb1tO6U/SqXY--
]]
CHUNK[[
--1S8dCMR/31oAAAAApHRNMETjK2uRsQs4mVVFKVNujcqnm8FHOXWvqARiaYy9ZmnpQ7uQ
]]
CHUNK[[
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset=utf8
Content-Disposition: attachment; filename="example.c"

]]
CHUNK[[
int main() { return 0; }]]
CHUNK[[

]]
CHUNK[[
--1S8dCMR/31oAAAAApHRNMETjK2uRsQs4mVVFKVNujcqnm8FHOXWvqARiaYy9ZmnpQ7uQ--
]]
...