By not advertising SMTPUTF8 support at the start, senders may opt to transmit recipient internationalized domain names in IDNA form instead, which will be deliverable.
Incoming mail with internationalized domains was probably working prior to our move to Ubuntu 18.04 when postfix's SMTPUTF8 support became enabled by default.
The previous commit is retained because Mail-in-a-Box users might prefer to keep SMTPUTF8 on for outbound mail, if they are not using internationalized domains for email, in which case the previous commit fixes the 'relay access denied' error even if the emails aren't deliverable.
When an email is received by Postfix using SMTPUTF8 and the recipient domain is a Unicode internationalized domain, it was failing to be delivered (bouncing with 'relay access denied') because our users and aliases tables only store ASCII (IDNA) forms of internationalized domains. In this commit, domain maps are added to the auto_aliases table from the Unicode form of each mail domain to its IDNA form, if those forms are different. The Postfix domains query is updated to look at the auto_aliases table now as well, since it is the only table with Unicode forms of the mail domains.
However, mail delivery is still not working since the Dovecot LMTP server does not support SMTPUTF8, and mail still bounces but with an error that SMTPUTF8 is not supported.
They really should never have been conflated with the user-provided aliases.
Update the postfix alias map to query the automatically generated aliases with lowest priority.
And write MIAB dns zone config into /etc/nsd/nsd.conf.d/zones.conf. Delete lingering old zones.conf file.
Co-authored-by: Joshua Tauberer <jt@occams.info>
