Milter-greylist

ED> Another example, which is a bit less satisfying
ED> acl blacklist dnsrbl knownspammer.example.net
ED> acl whitelist dnsrbl friends.example.net
ED> acl greylist rcpt john.doe@... dnsrbl dslpool.example.net delay 1d
ED> acl greylist rcpt john.doe@... delay 45m
ED> acl greylist rcpt manu@... dnsrbl dslpool.example.net delay 1d
ED> acl greylist rcpt manu@... delay 45m
ED> acl whitelist default
ED> Problem: we have to duplicate a lot of informations. Obviously there is the
ED> need for some factoring syntax. Any comment or idea?

Something like

acl greylist rcpt {
        john.doe@...,
        manu@...
} dnsrbl dslpool.example.net delay 1d

maybe?  I.e. let the user make lists of rcpts, addrs, and domains,
perhaps even named lists, such as:

list example rcpt { john.doe@..., manu@... }
acl greylist example dnsrbl dslpool.example.net delay 1d
acl greylist example delay 45m

It seems to me a bit similar to named.conf syntax.

"Consulting" DNSBLs is a great idea, but I think it would also be
the opportunity to implement some resource limit features, such as
the maximum possible greylisted/whitelisted tuples, since delaying
to DNSBLs (instead of just dropping connections) may increase the
number of recorded tuples dramatically.

P.S. IMHO blacklist acl is very much needed even without variable
greylisting...

Best regards,
Denis Solovyov