1and1.com refuses to accept email from a host without a valid reverse DNS record
From the mail log:
Jun 26 10:04:38 p2-wiki-nyc1-01 postfix/smtp: EA8972047F: email@example.com, relay=mx01.1and1.com[188.8.131.52]:25, delay=4594, delays=4594/0.01/0.26/0, dsn=4.0.0, status=deferred (host mx01.1and1.com[184.108.40.206] refused to talk to me: 554-perfora.net (mxeueus002) Nemesis ESMTP Service not available 554-No SMTP service 554 invalid DNS PTR resource record, IP=220.127.116.11)
I've opened a ticket with Digital Ocean to inquire about their recommended configuration, but it really comes down to configuring the applications, the hostname (FQDN) and forward-zone DNS for each domain (MX records). So I might have to reconfigure the wiki application to correspond with the domain MX records; or configure Postfix on the host to send mail for na-mic.org through the MX provider for na-mic.org.
Currently na-mic.org has MX handled by public.kitware.com Are there any actual na-mic.org user email accounts? (e.g. joe @na-mic.org or firstname.lastname@example.org) If not, we could also just change the MX record for na-mic.org to point to this host.
See https://mxtoolbox.com/domain/na-mic.org/ for more DNS and Mail info and tools.
As an aside, I renamed the host to qb; (it was p2-wiki-nyc1-01)
dig -x 18.104.22.168 +short
CC: @mhalle for potential DNS changes