How do I change the time zone for mail.log files?

Question

I'm using Debian buster. I changed the time zone with timedatectl and restarted postfix and dovecot but log records in mail.log are still showing UTC time. How do I fix this?

Answer 1

Restart the log server that actually writes the log entries (in your case, probably rsyslog).

It was not the daemons postfix and dovecot that generate the timestamp, they just put their messages into syslog and rsyslogd proceded to format them with its configured time stamp format (and currently selected timezone translation).

General solution: To know which service exactly is writing to a file, it is often helpful to use lsof, e.g.:

lsof /var/log/file
lsof +D /some/directory/and/all/below/