[Mimedefang] Can MD/SA combo detect no reverse ip?

[Tony Langdon]

> little thought: it makes sense to test such relays without 
> reverse dns for 
> an open port 25. if there is no open port 25, those ips are 
> almost always 
> open proxies (which usually do nothing else than injecting spam). 

Hmm, that's also going to knock out some home LAN users (like myself) who
run their own local copy of Sendmail for outbound delivery, but don't accept
mail.  I have port 25 firewalled off from the outside world, as does the
cable ISP.

The reasons for using sendmail this way are twofold:

1.  faster access (LAN is faster than the upstream speed of the cable
modem), so the MUA isn't tied up for as long with large messages.

2.  I have several email addresses in different domains, so I want to ensure
that I can send mail from all of them, without my ISP's mail servers
thinking I'm attempting to send spam and blocking such emails.  This one
precludes the use of a "smart host" (DS) in /etc/mail/sendmail.cf.

The IP address I use does have a reverse DNS (of the ISP), but that means it
only matches the sender's domain part of the time

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