New comment by ffobzb on void-packages repository

https://github.com/void-linux/void-packages/issues/39918#issuecomment-1967551161

Comment:
After a short break of several months :-) I picked up this issue again. I think I found the reason for the behaviour and a suitable workaround.

The chroot'ed processes can't access `/etc/localtime` and thus fall back to UTC. This shall be prevented by the call of `tzset(3)` before the chroot, and on OpenBSD this works. But in GNU libc the behaviour is - as far as I understood it - different: If the environment variable `TZ` is not set, then each call of a time-related function looks up the time zone again, and this fails after the chroot because `/etc/localtime` isn't accessible. This means that the `tzset()` call before is useless in case of GNU libc.

If `TZ` is not empty and is set to a timezone string before starting smtpd then all works as expected: Mail headers and log entries have the times in the configured time zone. This also works when TZ is set to the filespec format (see `tzset(3)`).

So the workaround is as simple as setting `TZ` before starting smtpd:

`# TZ=/etc/localtime smtpd`

And the corresponding entry in `/etc/sv/opensmtpd/run` then should be:
`TZ=/etc/localtime exec smtpd -F 2>&1`