stunndard/cocosmail

Golang SMTP server

cocosmail's Issues

Use separate SSL certs for SMTP, POP3

Use separate SSL for EACH listening endpoint, be it SMTP, POP3 or anything else.
It should be possible to use a separate SSL cert for EACH listening endpoint.
For example, for a multihomed, multi-IP host that uses different hostnames for different IPs, and/or SMTP/POP3 listeners.

"Received:" header with ESMPTS is bogus

Received: from mail-yb1-x.x.xx. ([xx.xx.xx.xx] helo=[xxx])
        by unknown with ESMTPS (unknow unknow)   <-- here
        (cocosmail 0.2.0)
        (envelope-from [email protected])
        id ....
        for ...; Wed, 09 Jun 2021 06:27:02 +0200

This seems to affect messages received with STARTTLS only.

ipv6 support

Make sure it works for ipv6-only and dual socket configuration.

High CPU usage on receiving mail with SMTP

I'm getting 100% CPU usage when sending an email from a client to cocosmail server with SMTP. Peaking around 600Kbyte/sec.

Refactor `func (s *SMTPServerSession) handle()`

Goroutine and exitasap channel seem completely non-necessary there.

Implement different system name for each listening/delivering IP

cocosmail can listen on several IP addresses at the sime time. Make it possible to use different mail system name for each listening IP.

<connect to listening ip1>:
220 cocosmail.domain1.io ESMTP - f3838fc0b51467288d7ef58f8b4b3b5759e72753

<connect to listening ip2>:
220 another.mail.io ESMTP - f3838fc0b51467288d7ef58f8b4b3b5759e72753

use systemd sockets on the linux

https://stackoverflow.com/a/41890792/6419273
https://pkg.go.dev/github.com/coreos/go-systemd/activation

Add connection delays in case of failed AUTH and RCPT TO

There are delays with failed MAIL FROM, but not in case of failed AUTH, despite the connection is terminated. There also no delays (and no termination) in case of failed domain or user in RCPT TO.

Malformed email addresses allowed in MAIL FROM

Multi @ is allowed and other issues

220 tmail.io ESMTP - f3838fc0b51467288d7ef58f8b4b3b5759e72753
mail from:<
250 ok
mail from:<addr@domain@[email protected]
250 ok

Implement plugin interface

Plugin system needs to be reworked so it can use some embedded scripting language for every hook that is called during the life cycle of a message.

Graceful shutdown

Implement a graceful shutdown, any pending tasks should complete cleanly without data loss.

disable AUTH in non-ssl sessions

do not accept AUTH in non-encrypted sessions from public IPs.
make it configurable?