I try to setup server side email synchronization on a CRM 2015. But when testing the Mailboxes there are errors (both on in- and outgoing tests) but a least I found out what the problem on the outgoing SMTP is. I traces networktraffic and when sender email is posted to the mail server it responds this way:
5.7.1 <email-address>
Recipient address rejected: Mail appeared to be SPAM or forged.
Ask your Mail/DNS-Administrator to correct HELO and DNS MX settings or to get removed from DNSBLs;
MTA helo: computer-name, MTA hostname: unknown[ip-address] (helo/hostname mismatch)
Of course email-address, computer-name and ip-adress are placeholders for real values.
CRM sends the CRM instance name (which also is the computer name and not a value which could be resolved per DNS) as helo, what I think causes this problem. The helo/hostname mismatch should be solved when the IP would be send as helo, shouldn't it?
How can I make the CRM using anothers value as helo? Is there a way to configure this?