>we receive spam from some accounts that belong
>to those domains...

maybe, maybe not.   you have to look at all the delivery headers to know 
whether the msg is really from bigISP ip addresses.

In IMGate, we have a new anti-spam filter:  when the envelope 
@sender.domain alleges to be one of 4400 frequently forged domains, IMGate 
will reject the msg if the sending's ip PTR and A record don't match.

Going further, I have a shell script that harvests the sender's ip from the 
above rejects and blacklists that ip's entire Class C.

BOFH rules apply at all times!

Len

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