Bugzilla registrations fail on sender verified systems due to buggy sender for registration email verification mail:
response to "RCPT TO:<bugzilla-daemon@bugs.documentfoundation.org>"
from bugs.documentfoundation.org [2a00:1828:a012:150::1] was:
554 5.7.1 <bugzilla-daemon@bugs.documentfoundation.org>: Relay access denied
Please fix your virtual hosts or MXes.
Thank you!
(Obviously I cannot open a bugreport of this…)