So I had this brainwave and thought it’d be a good idea to set up a Pi as an e-mail server. After all, how hard could it be, there are hundreds of thousands of mail servers around the globe that work well. What could possibly go wrong ?
I started out trying to keep it simple. I’m pretty familiar with Sendmail but I figured that I’d go with something simple as I was only going to serve two users and Sendmail seemed a lot of overkill.
After a bit of searching Citadel seemed to fit well. I installed it and configured but there is no way I could get past a couple of errors not the least if which is “db:cursor still in progress on cdb 02: attempt to write during a r/o cursor”. I tried a completely fresh install of Raspbian Buster with a brand new install of Citadel. Still no dice. Searched for more comprehensive doco but, again, to no avail. I reckon I just about wore out the search engines looking for a solution but still no illumination. I even tried downloading the source and buildin it from scratch. The same olf “db:cursor still in progress…” error persisted.
Scratch Citadel which is a pity really as I reckon it’d be the bees knees for a simple and small e-mail server.
On to Dovecot and Postfix. I had a few issues but by carefully following the documentation on Postfix.org I had it all up and running. In the beginning I had a lot of trouble getting “saslauthd” to do the authentication and I spent a goodish amount of time trying to treat the symptoms without success. At this point I decided to get rid of postfix and dovecot and start again from a new install of both. The big difference this time was that I folloed the docs on postfix.org to the letter. Surprise, surprise it all worked as it should.
After years and years of telling people to RTFM I didn’t.Once I did RTFM I proved my own point yet again.
Now came the hard part. DNS records. I use a dynamic DNS which has served me very well thus far. Setting up the MX record was very easy but I discovered I needed a PTR (for reverse lookups) and this is where the gremlins started to creep in. I needed a static address. No problem just ask my ISP, right ? Easily doable, for another ten bucks a month. Sign the static IP over to the dynamic DNS provider so that they can use it for all DNS records. ISP says – “oh no we can’t do that”. Luckily my dynamic DNS provider has a facility that can easily get around that particular scenario.
Now that it all works, I’m happy and am quite willing to advocate for the Postfix / Dovecot sulution. It’s a lot easier to configure than Sendmail. The configuration files are well commented and make sense, unlike Sendmail.
If you’re considering setting up your own mail server first check that you can get a PTR DNS record. If you can’t look for another solution. If you can, RTFM and pay attention to the details and recommendations.
Just for fun and games on our internal network I set up a DNS complete with MX and PTR records and with the internal e-mail system configured to insist on reverse lookups it worked perfectly with no errors. Of course this was only with two Pi’s, two PC’s and two windows tablets. I’ve got rid of it all now I know how to make it work and that there’s no point with an uncooperative ISP.
