FSCI mailing list service was deployed in 1 July 2018. From the start
list was struggling with DKIM validation. All the domain hosted with
lists.fsci.org.in has DKIM signature and it signs (its own) outgoing
mails ie notifications, digest mails. But Mailman adds header, footer
etc to the subscriber's original mail which breaks the DKIM signature
causing mails to end up in spam/junk box (especially in gmail).
This mailing list runs on Debian unstable. Around October the unattended
upgrades automatically updated mailman3 which caused several services
within mailman to crash. I had no idea what happened until Praveen
investigated and told me so. We quickly updated every piece of mailman3
and restarted the service and brought web, archiving services back to
life but the most vital role of mailman was not working ie distributing
emails. Malayalees would enjoy following line for this situation.
റെക്കോർഡിങ് വർക്ക് ചെയ്യുന്നില്ല എന്നായിരുന്നു കംപ്ലൈന്റ്റ്
I tried every suggestion I got from forums, blogs but no joy. I left it
there and carried away with other duties of my life. The first issue
shows lack of sysadmin magical skills. The second one shows my
carelessness. Point is, more volunteers needed.
Recently someone posted in our matrix channel questioning the stability
of FSCI's services. This gave me a fire to start on these issues again.
The first approach I took was to take the back up and build from the
scratch as I forgot where I stopped. But it is not a good approach as I
couldn't find the root cause and if the same issue pops again in future
I can only do the same. So I tried harder in investigating logs. I was
also getting help from upstream mailman devs. A lot of mails exchanged
on their list and off list.
While working on this, I got a lead to the DKIM issue. Thanks to this
blog. I finally figured out to sign every outgoing mail from the server.
Today this thread got my attention. I looked through templates of
lists.fsci.org.in. and deleted the custom one and changed permissions of
generic ones (From 3.2.0 every lists/domain templates can be customized
Finally mailman is distributing mails. Thanks to all who helped me. For
now every known issue is cleared.
 - https://packages.debian.org/sid/unattended-upgrades