Thus spake Stephen J. Wilcox (steve@telecomplete.co.uk) [18/09/03 18:54]:
So totallymadeupdomain.com now resolves but is unreachable. That will prevent you from bouncing emails to non-existent domains immediately..
FWIW, the latest versions of postfix have code in them to block connects from explicitly listed hosts: New check_{helo,sender,recipient}_{ns,mx}_access maptype:mapname restriction that applies the specified access table to the NS or MX hosts of the host/domain given in HELO, EHLO, MAIL FROM or RCPT TO commands. This can be used to block mail from so-called spammer havens, or from sender addresses that resolve to Verisign's wild-card mail responder, currently at IP address 64.94.110.11. - Damian