[Mimedefang] Verizon and greylisting

[Whit Blauvelt]

Since instituting greylisting I've noticed mail to verizon.net sometimes
getting refused (with the blunt message "You are not allowed to send mail").
Googling around, it turns out that verizon.net has a practice, when it sees
incoming mail, of beginning to send mail back to the "from" address - from a
different server than the one receiving the incoming mail. If Verizon then
sees any sort of error code as a result of its own attempt, it rejects the
incoming mail - and a greylisting message counts as an error to their
brain-dead code.

What I'm now trying (unproven) is:

if ($RelayHostname =~ /sv[1-99]pub.verizon.net/) { return ('ACCEPT_AND_NO_MORE_FILTERING', 'OK'); }

before the greylist code.

What with Verizon being the top service for spammers according to Spamhaus
- http://www.spamhaus.org/statistics/networks.lasso - I suppose they're
trying extra hard to squelch the incoming competition for their spam-sending
customers. Hopefully those customers aren't using Verizon's relays, that
I've now lowered defenses to?

Sigh,
Whit