| # maitred |
|
| Lightweight embeddable SMTP [RFC5321](https://www.rfc-editor.org/rfc/rfc5321.html) |
| server for use in applications that need to receive e-mail. |
|
| ## Use Case |
|
| The original goal of this library is to have a usable SMTP server that can be |
| embedded in mailing list software, particularly for use in |
| [Ayllu](https://ayllu-forge.org) and |
| [Mailpot](https://git.meli-email.org/meli/mailpot). After considering all of |
| the existing SMTP servers there was no Rust library that could be easily |
| embedded in an application and general purpose SMTP servers like Postfix are |
| too complex to be reasonably packaged. |
|
| ## Security |
|
| ### Relaying |
|
| Due to the common abuse of the SMTP protocol by nefarious internet actors the |
| default behavior of this package must _never_ allow open relaying without |
| explicit and conscious configuration from the user. Additionally the SMTP |
| server must never expose the e-mail addresses or other user data contained |
| within. |
|
| ## Alpha Status |
|
| This library is in an "alpha" state currently and should not be considered |
| stable until it reaches version `1.0`, use at your own risk! |
|
| ## Protocol Status |
|
| ### SMTP Base server and Commands [RFC5321](rfcs/rfc5321.txt) |
|
| | Name | Status | Notes | |
| |-----------|--------|-------------------------------------------------------| |
| | HELO | ✅ | | |
| | EHLO | ✅ | | |
| | MAIL | ✅ | | |
| | RCPT | ✅ | | |
| | BDAT | ✅ | | |
| | DATA | ✅ | | |
| | AUTH | ✅ | SASL PLAIN only | |
| | VRFY | ✅ | | |
| | EXPN | ✅ | | |
| | STARTTLS | ✅ | | |
|
|
| ### ESMTP Extensions |
|
| | Name | Status | RFC | |
| |-----------------------|----------|-------------------------------| |
| | SIZE | ✅ | [RFC1870](rfcs/rfc1870.txt) | |
| | PIPELINING | ✅ | [RFC2920](rfcs/rfc2920.txt) | |
| | 8BITMIME | ✅ | [RFC6152](rfcs/rfc6152.txt) | |
| | ENHANCED STATUS CODES | ⚠️ | [RFC2920](rfcs/rfc3463.txt) | |
| | SMTPUTF8 | TODO | [RFC6531](rfcs/rfc6531.txt) | |
| | CHUNKING | ✅ | [RFC3030](rfcs/rfc3030.txt) | |
| | DSN | TODO | [RFC3461](rfcs/rfc3461.txt) | |
| | ETRN | ❌ | [RFC1985](rfcs/rfc1985.txt) | |
| | ATRN | ❌ | RFC2645 | |
| | BURL | ❌ | RFC4468 | |
| | REQUIRETLS | TODO | [RFC8689](rfcs/rfc8689.txt) | |
|
| ### Authentication Extensions |
|
| All authentication extensions are implemented with the |
| [mail-auth](https://crates.io/crates/mail-auth) package from Stalwart. |
|
| |name | status | |
| |---------------------------|--------| |
| | DKIM Verification | ✅ | |
| | ARC Chain Verification | TODO | |
| | SPF Policy Evaluation | ✅ | |
| | DMARC Policy Evaluation | TODO | |
|
|
| ### TLS Configuration |
|
| STARTTLS is supported for upgrading plain text connections (opportunistic TLS). |
|
| Implicit TLS on a dedicated port is a WIP. |
|
| ### Proxy Protocol |
|
| Often times you don't want to bind directly to privileged port `25`. Maitred |
| provdes support for HAProxy's |
| [PROXY protocol](https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt) |
| which lets you proxy traffic from Nginx (or HAProxy) and expose the client's |
| original source IP address. This is required for SPF session level validation. |
|
|
| ## Attributions |
|
| Several of the free software libraries released by |
| [stalwart](https://github.com/stalwartlabs/mail-server) are in use here. |