Comment 2 for bug 1636689

Thank you for taking the time to report this bug and helping to make Ubuntu better.

This looks like local corruption or misconfiguration, rather than a bug in Ubuntu. You can find pointers to get help for this sort of problem here: http://www.ubuntu.com/support/community

From your log:
Oct 26 09:13:04 hostname systemd[1]: Failed to start LSB: saslauthd startup script.
Oct 26 09:13:04 hostname systemd[1]: saslauthd.service: Failed with result 'exit-code'.
Oct 26 09:13:40 hostname saslpasswd2[18454]: error deleting entry from sasldb: BDB0073 DB_NOTFOUND: No matching key/data pair found

Unfortunately it is hard to help in form of a bug report - it very much seems like a local configuration issue.
You say it worked before - before what - the last update?

It also seems some DB or DB key isn't found - since you purged and reinstalled anyway - could it be that some old broken content is still left?

If you believe that this is really a bug, then you may find it helpful to read "How to report bugs effectively" http://www.chiark.greenend.org.uk/~sgtatham/bugs.html. We'd be grateful if you would then provide a more complete description of the problem, explain why you believe this is a bug rather than a problem specific to your system, and then change the bug status back to New.

The steps to reproduce didn't trigger the problem for me, so there is little that can be done on this bug. I'll mark this bug as Incomplete for now, pending someone else confirming that it is a bug or unless someone can provide steps to reproduce.

Please do report any other bugs you may find.