Outbound IP different from static IP
We have the single static IP option.
We recently started having a problem where outgoing mail is always rejected by the recipient server. While investigating the cause, I made the discovery that our outbound IP address as seen by the peer computer is different from our static IP address. This was seen by the rejection letter, and confirmed by browsing to whatismyip.com.
The address mangling causes us to be rejected on the basis that "if this is a Comcast IP address, you must send mail through the Comcast SMTP server." Well, that is not an option either, since we do not have a Comcast email address nor do we have Comcast hosting our domain email.
What causes the address to be NAT'd for outbound connections, and how can I turn that off?
1 year ago
Greetings, @WendyB! Thanks so much for taking a moment out of your busy day to leave a post on our community forum. I'm sorry to hear you're having issues with your outbound IP address, but you have definitely come to the right place for assistance.
You mentioned this only started happening recently. As far as you can tell, did your outbound mail previously originate from your static IP address, only to change to this new one, or was this just happening without errors up to this point? Has there been any change to your service, software, or equipment, prior to this occurring?
1 year ago
I can't say for sure that the static IP address used to be seen as the outside source, but there were no internal changes before this happened. It is possible that Spamhaus, among others, have recently implemented new restrictions on who can relay mail. But unfortunately, that still puts us in a bind. Certainly, having our static IP address as the source should go a long way towards improving our server's "reputation" among recipients since we at least have RDNS in place.