For some reason overnight my system decided to block relayed e-mails.
At present (until the server is upgraded) the smtp server is our ISP which then relays e-mails back to us to send to someone internally (not everyone has yet upgraded to Scalix Connect)
Jun 21 13:15:22 mail sendmail[11163]: l5KMbrhP003152: to=<admin@mail.otherdomain.org.nz>, delay=02:37:28, mailer=local, pri=1412025, dsn=5.1.1, stat=User unknown
Jun 21 13:15:22 mail sendmail[11163]: l5KMbrhP003152: l5L0wM7H011163: postmaster notify: User unknown
Jun 21 13:20:43 mail sendmail[14743]: l5L1KNPc014743: ruleset=check_mail, arg1=<first.last@domain.co.nz>, relay=localhost.localdomain [127.0.0.1], reject=553 5.1.8 <first.last@domain.co.nz>... Domain of sender address first.last@domain.co.nz does not exist
All the current e-mails stuck in the queu just keep bouncing around also.
So far it seems that internal e-mails exit FROM user1@domain.co.nz
Return saying from user1@mail.otherdomain.org.nz
Then just send back an error saying that it's failed.
The strange thing is that nothing has really changed.