I'm running php mailer on a site we built and need to know if the email I'm sending is bouncing. This is not spam! I'm sending legit mail. A 'bounce' message is the only way I have of knowing if the recipient's email address has been correctly entered into our system.
From my desktop (Outlook) I can send and receive mail to the box in question including bounces (firstname.lastname@example.org) but when php mailer (set to show as being sent from email@example.com) sends to an incorrect address the bounce message never comes back to the firstname.lastname@example.org box.
Are you setting a 'reply to' address in your mail headers? I think if you do not set this most email clients will use the 'from' address as the reply to. I'd check it if you are not getting bounced reply.