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Comment by dcw303 | Hacker News Reader

I'm a docker newbie and I had a hare-brained idea to install postfix and dovecot in a container. I thought it would be neat to version/deploy the various config necessary on top of a clean OS install. As I'll probably mess it up the first time, a quick way to blast the system clean is appealing.

If I can keep credentials and data outside of the container, is this still a bad idea? Would I run into trouble with other containers needing to use SMTP?

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The biggest problem you will have is that a lot of critical SMTP functionality (SPF, DKIM, DMARC, antispam blackhole lists, SSL certificates, email addresses themselves) rely on DNS. So instead of testing with just a container, to get any meaningfully useful notion of reliability and/or applicability to the real world for your container you will have to test with entire fake DNS infrastructure and multiple hosts. While you could technically do it, the reality is you're entering a world of pain.

Currently setting up a mail-server myself, the majority of clients are in China but I want reliable sending to foreign servers: it's quite difficult. Like finding a host, when so many Chinese IP ranges are blanket blacklisted by western mailservers, and the China/foreign link is often slow/overloaded/lossy. Taking the time to update Gentoo postfix documentation en-route, for the other DIY'ers with an NCH (not compiled here) problem. Not using docker.

I've run simple SMTP from a container and not had any issues. I've not tried a more complex stack (but I have thought about it... ) and I was looking at this project

https://github.com/tomav/docker-mailserver

I'm afraid I can't account for it - having never tried it, but it looks like the sort of thing you might be interested in!

PS If you are a newbie, do try something simple first - it took a while to get my head around the differences in the docker tooling (for example this project uses docker-compose which is another tool on top of the docker cl tool).

EDIT: Ooh - a tutorial

https://tvi.al/simple-mail-server-with-docker/

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