during the update the log_warnings changed from 1 to 2 therefore
showing lots of aborted connection notices in the logs
changing the log_warnings back from 2 to 1 solved this issue
Yes the same setting made the same change to the default with mysql:
https://dev.mysql.com/doc/refman/5.7/en/server-options.html#option_mysqld_log-warnings
So now we know how to silence the "Aborted connection" mysql loglines
thank you!
But still I wonder if Dovecot wants to handle these connections slightly
differently - if it could be cleaner? Or is it moot?