our mailserver rejects mails from servers that don’t send a resolvable HELO-hostname.

As such, customers have been complaining about UPC:

     450 4.7.1 <vie01a-dmta-ch01.mx.upcmail.net>: Helo command rejected:

From this posting, although a bit dated:

it looks as if there is some sort of typo or it was simply forgotten to update DNS.

Can someone fix this?

Rainer