This is probably really obvious... I have two MX machines, call them mx0 and mx1; mx0 is the lower-priority and does deliveries to users. As is the way of the world, mx1 gets hit by a lot of spammers with scraped addresses which will be undeliverable (e.g. message-IDs). At the moment, mx1 accepts the message (assuming it passes the spam filter), and forwards it to mx0, which rejects it; then mx1 tries to send a bounce message to the (faked) originator.
Is there a way of letting mx1 know what addresses on mx0 are valid, so that it can refuse the message while the SMTP session is still live? -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
