We've got a SBS 2011 that we're having the odd issue with sending/or receiving.
It seems to be since we subscribed to Avira Managed Email Security.
We're now using Avira for first 2 entries of MX records but have the native server: "mail.domain.com" as the 3rd.
Avira seems to make no mention of making changes to any records except MX records.
Should I be changing reverse DNS to point to them? Should I be making other changes?