My company can't email to a particular domain and we are getting the following error:
550-No such person at this address" 550 Sender verify failed ##
We use Exchange 2007, Forefront Server Security, SBS 2008 and Smoothwall Corporate Firewall 5.
Is there anything that I can do at my end to facilitate what seems to be "Sender Address Verification".
My MX record is correctly pointing to an A name.
If not, then what do I need to ask the other domain to do? They insist that it's my problem, so I need to be specific. We have no problems emailing other domains, and they seem to be able to email to us successfully.
BTW I have checked 122 SPAM Blacklists and we are not on them