From: "Trevor Toenjes" <zope@toenjes.com>
I like the idea of having this capability. Having the option to integrate it into sendmail or as a standalone scrubber would be ideal. Could this become a product?
Uhm, no, I don't think so. This is more a question of weather to add an option to make MailHost/sendmail fail if one reciepent is rejected or only when all recipients are rejected as it is today. I'm still not sure it's a very useful idea though. :-)
Next week I get a new list of 500 emails that has never been tested. I would like to do an SMTP handshake(without sending) to verify the domains/addresses that will accept the emails, and remove the addresses that fail. This makes bounce management much cleaner and lowers overhead when you actually send the messages.
If you call sendmail directly without going through MailHost you will get a list back of the rejected recipients. Maybe you could use that?