6.6.3 seems to have changed the way offline directory is handled. smtpctl has incorrect permissions (with possible security implications):
# ls -l /usr/local/sbin/smtpctl
-r-xr-sr-x 1 root wheel 222832 Feb 15 08:23 /usr/local/sbin/smtpctl
It has setgid wheel when according to https://github.com/OpenSMTPD/OpenSMTPD/issues/839#issuecomment-371159242 it should be setgid _smtpq.
This results in an error when, for example, PHP mail() is used:
sendmail: cannot create temporary file /var/spool/smtpd/offline/whatever.whatever: Permission denied
(In reply to Kamigishi Rei from comment #0)
Did this issue was gone with 6.6.4 pkg release?
(In reply to Dima Panov from comment #1)
I think so; the smtpctl binary seems to have correct permissions now.