Got a question about blacklisting behaviour. Internet MX records for "mydomain.com" point to my anti-spam gateways. The anti-spam gateways then relay the email to my mail server. If someone sends an email to ,say, firstname.lastname@example.org the email is first accepted by the anti-spam gateway, but it will then be rejected by the downstream mail server because the recipient does not exist.
Now, my colleague says that he's seen this behaviour result in a mail relay getting blacklisted (he gave AOL as an example). I have not seen this myself, but I'm not sure if its because I've been lucky or if its because he's wrong. Can anybody clarify this?