I just did another little test. I sent an email to
fsfsdf@kimrichards.net using my ISP as the mail server and still got the same bounce message saying:
Reason: "The recipient cannot be verified. Please check all recipients of this message to verify they are valid."
I changed the mail server to my own, on the same server, and the message didn't even get sent. I got a popup saying the exact same thing. Means my server checked for the existance of the email address BEFORE accepting the email, which is how it works now, and didn't even accept the email.
Almost looks to me like the new mail system, how it checks before accepting the email, doesn't allow custom fail messages.
To anyone out there who has an address set to fail with a custom message, if you send an email to that address, do you get the custom message, or do you get the default one like I got?