I was using an old version so I followed the migration page and migrated to the latest LTS version. The problem is with Mailman. When I restored my backup the mailman part failed. When I recheck the configuration I get this.
.. your system is not ready for use by Virtualmin : Plugin virtualmin-mailman cannot be used : The mailman program /usr/lib/mailman3/bin/mailman was not found on your system.
I noticed it said mailman3 in the path it is looking for, but when I was looking the forum post said mailman3 wasn’t the right one. Did that change? So my question is how do I install mailman and is there a way to get my mailing list back without touching the website?
The version of Mailman provided by your OS is the version you should use. You saw an old forum post from before the Virtualmin Mailman plugin supported Mailman 3 and before it was widely available on supported distros (I guess).
Did you install the Mailman package from your OS repos? Our installer no longer installs Mailman, as it is so rarely used.
The same way you install anything: Using your OS package manager. sudo apt install mailman3 is probably the thing, though I haven’t used Mailman in years and don’t have Ubuntu servers handy to check.
Last I knew, Debian (so maybe Ubuntu?) didn’t touch the Postfix configuration. Putting the maps statements at the end of the configuration (main.cf) may be a mistake. Virtualmin seems to have a default catchall that will kick in prior and mailman will never get that far.
Going from memory, always questionable, if you were on mailman 2 it isn’t very backwards compatible with 3. Knowing mailing lists were going out of fashion they tried to make it a quasi forum thing. It isn’t exactly backwards compatible.
There is a migration process, but I’m not super familiar with it (the last Mailmain list I maintained was pre-Mailman 3). We don’t really try to deal with that, as it’s quite complicated and we no longer ship Mailman as part of the regular Virtualmin stack (and almost no one among our users uses it).