this post was submitted on 13 Aug 2023
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My own mail server (self.selfhosted)
submitted 1 year ago by Trondk to c/selfhosted
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I have run my own mail server now for 20+ years. its is runnig postfix , with spamassain. the users have imaps, and roundcube www gui.

It had been running fine, and have been updated HW / OS a lot of time over the years, now its runnig on rocky O/S

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[–] [email protected] 5 points 1 year ago* (last edited 1 year ago) (1 children)

Well I didn’t want google to read my mails

Sadly, it only works if no one in the recipients of the mail is on gmail (or if everyone use pgp, which I would tend to think is even more rare).

I host my own mailserver as well, and I would add as benefits:

  • creating as many email address as you want easily, possibly regexp based address (awesome to give every site a different address and know where the spam comes from, without using the well known schema username+something@host). That also makes routing/filtering mails way more easy, you just have to match the recipient address.
  • delivering mails to software, to put email at the center of interapps messaging (basically, that means that postfix pass a matching email to the executable of your choice on your system instead of storing it in your mailbox)
  • advanced rules for handling emails. When I want to block a spammer that managed to get my real email, I use regexps to match their mails and reject it with a "REJECT 5.1.1 Recipient address rejected: User unknown in local recipient table" error, imitating the error for unknown users, which often triggers a mail system to remove your address from their database
  • easily configure apps to send me email. When I write an application that will send emails to me and only me, I configure it to use my smtp on port 25 without authentication instead of the usual smtps configuration they expect. It connects to it and asks to send a mail to me, which is accepted since I'm a local user. It makes everything way easier (try to do that with gmail and get your IP banned)
  • easy backups. Both of the mail system (I backup the whole sdcard of the pi) and of the emails. Never lose an email again.
[–] [email protected] 2 points 1 year ago (1 children)

Are there any good recources on how to host you e-mail-server?

I guess slapping it on my local raspberry pi wouldn't be enough no? So you probably need a quite sophisticated setup so that there are no downtimes?

[–] [email protected] 4 points 1 year ago (1 children)

I guess slapping it on my local raspberry pi wouldn’t be enough no?

Oh no, that would be way not enough. :) Managing a mailserver is a sysadmin task by itself. While you don't need to do much once it works (which often is a perk of sysadmin work, compensating for the fact that when it does not work, they may have to wake in the middle of the night to fix it), it's notoriously difficult to get right : you have the configuration of the mailserver to get right first, so that you can send emails, but nobody else can and you don't become a spam relay without knowing it. Then you have a lot of configuration to do to be able to retrieve your emails from your server, which uses other protocols that you must learn about. Then you have "optional" things that you must setup (SPF, DKIM and DMARC), which you won't be able to send mails to gmail or outlook if you don't set them up properly. And when you will have got all of that right, you will have enough experience to be hired as a sysadmin. :)

I can't provide a good resource for learning it, I learned it 15 years ago when it was way more simple (before SPF and DKIM), and picked every addition as they appeared, but any course on how to manage a mail system will do. There is no difference in doing it for your self-hosted server and for a company (except maybe that for a company, they'll make you handle users in a database, which you can forego for your own needs). I would recommend to learn how to use postfix first, then any imap server (courier-imap is a top runner), and when you're comfortable with that, you can learn about SPF, then DKIM, then DMARC. But be aware before going through it that this is basically learning a new skill (sysadmin). You can find docker images that setup everything automatically for you, but I would recommend against that, because at some point, things will break and you will have no idea how to fix them. And if you try to fix them while not knowing well what you're doing, that's a good way to end up being a spam relay. Plus, those docker images are difficult to customize, which quite defeats the point of managing your own mail system to begin with.

[–] [email protected] 1 points 1 year ago (1 children)

Thanks for the long answer!

I haven't heard of most of your abbreviations/term till now so I guess this will be one of the bigger journeys through the world of IT :)

I do have to say for the purpose of tinkering I love these bigger projects because you learn so much on the way. Now having read your answer I am even more exited to try it out :D

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago)

I do have to say for the purpose of tinkering I love these bigger projects because you learn so much on the way. Now having read your answer I am even more exited to try it out :D

That's awesome to hear! Welcome, and have fun! :)

I haven’t heard of most of your abbreviations/term till now

Oh, my apologies. Here is a definition list :

  • SMTP : Simple Mail Transfer Protocol : the base of any mail system, it's the server you contact to send emails, which relays your mail to an other SMTP server (where your contact is hosted), which stores the mail for user to retrieve
  • IMAP : Internet Message Access Protocol : one of the protocols that can be used to retrieve emails from your mailserver (the other one being POP3)
  • SPF : Sender Policy Framework, a configuration on your domain name specifying which machines are allowed to send mails in its name
  • DKIM : DomainKeys Identified Mail : a signing process (signing each mail) to validate the "From" email address is indeed authorized from the domain it pretends to
  • DMARC : a warning system to let you know when someone pretended to be you (also giving instructions about what to do with emails when SPF and/or DKIM are missing or wrong)