We have a Fortimail 100c spam filter and Exchange 2007. Recipient validation is turned on within Exchange and working (returns a
550 5.1.1 User unknown) when tested using telnet and with our prior mail filter.
The Fortimail, however, is somehow able to submit mail to our Exchange server even to invalid addresses. Their support had me take a pcap of an email and I do indeed see a
RCPT TO:< invalid address > from the Fortimail and a "Recipient OK" back from Exchange.
So the question is: is there some setting in Exchange which would override recipient validation for a specific IP address? Any help would be greatly appreciated!