Major upgrade of mail server

[Steven Varco]

Hi Shawn

I recently did a similar upgrade project of a dovecot-postfix-amavis Mailserver from CentOS 6 to CentOS 7.

What I did was first creating a new test-server with the new OS.
Than I copied all the maildirs from the productive server to the testing server, so I could simulate the upgrade without any interuption for the users.

I then configured the new versions (specially dovecot) as close as possible to the old configuration.
=> Never introduce new features as part of an upgrade, as it complicates the upgrade and makes it much harder to trace errors.
If you want to use new features of the updated sofware plan the introduction of these as a new project after successful migration. For this you can easily re-use the test-server you’ve built in the first part to verify they will not break anything.

After I was confident, that everything will work, I planed a short downtime for the mail service over night, did a full backup and a VM Snapshot (very helpful, if you are running a virtualized mailserver!) and just re-installed the new OS, upgrading the server in-place.
After the imnstallation and initial configuration, I applied the new configuration to all mail components and testet each of them to ensure they are working properly.

good luck,
Steven

-- 
https://steven.varco.ch/ 
https://www.tech-island.com/ 

> Am 08.07.2021 um 03:15 schrieb Shawn Heisey <elyograg at elyograg.org>:
> 
> I have a mail server in AWS that is currently running Ubuntu 18.  Every time I log in, I am reminded that I can upgrade to Ubuntu 20.
> 
> On Ubuntu 18, the dovecot version is 3.3.0-1ubuntu0.3.  On Ubuntu 20, it is 2.3.7.2-1ubuntu3.  Many other packages, probably including the mysql server, would also be upgraded.
> 
> Dovecot and Postfix use a postfixadmin database in mysql for users, and postfix is using dovecot-lda to deliver mail.  I am using managesieve from dovecot on roundcube webmail.  As far as I know, my own user is the only one with sieve scripts actually in use ... and I have a LOT of filters/folders for various mailing lists.
> 
> I've been a little bit terrified of doing an upgrade, because I do have a couple of people using my mail server for real work email and I don't want to disrupt them.
> 
> I'm writing today to find out what are the likely pain points I might encounter when doing this kind of major upgrade, and if there is any helpful information that can help me get through those problems.  I'm hoping that it will go smoothly and everything just works.
> 
> Here's the doveconf -n output:
> https://apaste.info/FUgF
> 
> If I have been silly enough to include sensitive data from the config, I would appreciate a heads up so I know what passwords to change.  I did a quick glance and didn't see anything.
> 
> Thanks,
> Shawn