List, I operate a backup mx for one of my customers. In doing so, I have run into an issue where I must accept all email regardless of weather or not the messages is destined for a valid email account in my customers email system (which is MS Exchange 2003).
I thought about asking my customer is they would export a list of email addresses for which they want backup MX service for so I can place that in a relay_recipient_map, but that process requires ongoing admin time and might not appeal to them. The majority of the junk mail I am seeing is in the form of From: u...@domain and RCPT: u...@domain which is obviously forged. Would a header_check be the way to go here in order to match and discard the junk mail in this case? If so, what would the pcre check look like? I understand that legitimate users wouldn't be able to send themselves email, but that fine with me. best regards, _Terry