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Comment by lifty | Hacker News Reader

A very promising project is https://github.com/foxcpp/maddy. It is an all in one server that can both receive and send email.

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As mentioned in https://news.ycombinator.com/item?id=23960831 it's good for security to have SMTP server and IMAP server segregated, even separate physical machines, which you'll have a hard time doing when everything runs in the same process. What happens when maddy gets a security hole discovered.

To me maddy would feel like sleeping on live electrical wires, only they are insulated by a thin layer of paper. Hope the isolation does not get scratched anywhere while you sleep. Even a non-dockerized, traditional setup like postfix+dovecot has better isolation.

I believe a server wriiten in a memory safe language greatly reduces the risk of running such setup. To the point where it is an acceptable trade-off to get simpler maintenance.

Depending on how many targeted attacks you get in a day, you may pull apart the monlithic server and run inbound processing, filtering, IMAP access and outbound queueing as separate processes or even on separate systems.

(Probably i should put a better wording on https://foxcpp.dev/maddy/faq/)

You sir, created in me hope for mail server in Rust. But this is just a Go Lang

If I had an infinite amount if time, I would sure write maddy in Rust. But as practice shows, there are only around 24 hours in a day.

That being said, my project greatly benefits from Go concurrency features and simple I/O primitives. Also there are libraries written by emersion for nearly everything.

Oh when will this Rust hype end, November needs to come already.

Thanks for the tip.

> you may pull apart the monlithic server and run inbound processing, filtering, IMAP access and outbound queueing as separate processes or even on separate systems.

Can this be done without forking source code? E.g. just configuring two instances.

Thanks for the link to FAQ. Actually, simple, no bloat’ little dependency software definitely has some appeal.

Yes, this is possible.

This page shows how to configure maddy to only handle SMTP: https://foxcpp.dev/maddy/tutorials/smtp-only/ You can follow it but swap Dovecot for another maddy instance, configured as shown here: https://foxcpp.dev/maddy/tutorials/imap-only/

This works because maddy implements both client and server for Dovecot's SASL delegation protocol.

Alternatively you can configure pass_table to read from shared SQL database. Hm, maddy-tables(5) man page is not rendered on the website but you can look at sql_query module.

even separate physical machines

I think that is overkill for self hosting. Also as the author says below, Go is more memory safe than C/C++ in that there is no use after free and buffers are bounds checked.

Memory safety helps, but isn't the only source of exploitable bugs.

You would not really want so many "private" ports exposed on a public facing machine.

A machine which has IMAP open tends to look like it has some good stuff.

I just forward incoming emails to an internal SMTP server which also serves as IMAP server, so MX records won't simply reveal your IMAP server as well.

You can also just redirect receiving email from a public facing SMTP to an internal SMTP server which also runs IMAP.

This is actually how usual Postfix+Dovecot setup works in practice. Dovecot runs an LMTP server which is SMTP with some minor modificaitons. Postfix forwards messages to Dovecot's LMTP.

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