Milter-greylist

> PZ> I'd like to configure sendmail and milter-greylist, so that
> PZ> sendmail listens to two different IP-address, but have
> PZ> milter-greylist act on only one address.
> PZ> Is this a sendmail/milter configuration issue. or should
> PZ> this be handled inside the milter?
> 
> I'd probably run two instances of sendmail, each for its own IP
> address, with different sendmail.cfs given in command line...
> Can't remember another solution.

Sendmail looks to be able to tell milters the IP address of the local
side for each connection via ${daemon_addr}. If I am right, milters
can use it trivially. Alternatively, sendmail.cf hackers can write a
ruleset to define ${greylist} depending on ${daemon_addr}.

> To others: secondary MXes are often known to be less protected
> from spam, that's why many spammers prefer to send to secondary
> MX.

Another possible answer: primary MXes just reject mails to nonexistent
accounts but secondaries tend to bounce them. Spammers get the second
chance to deliver their mails.