Sendmail: How does one blacklist annoying spammers?

[Tim]

On Sun, 2010-06-27 at 08:24 +0800, Ed Greshko wrote:
> A well written greylisting milter will utilize a database to maintain
> a list of sending MTAs that have retried.  Additionally, the good
> milters will have the ability to specify whitelists and blacklists.
> But, even if you don't do the work to populate the lists this mostly
> results in only the very first message sent by a "trusted" MTA being
> delayed.  After the initial start-up, training period normal
> communication proceeds without delay.

Where greylisting, typically, becomes a cropper is when some *BIG*
service like Yahoo tries to mail you, gets grey listed, and it spits the
dummy about not being able to post (some do get pernickity about it,
with a low threshold for suspending posts that didn't immediately get
through).

Or, when it retries, the retry comes from a different server than the
first attempt, so that gets greylisted.  And your message plays "hot
potato" through several different servers, each one getting separately
greylisted.  If you're lucky, eventually it comes back through one that
your server will allow.  If you're not, it'll go through so many
attempts that your server disallows it for taking too long, or their
server aborts attempting because each attempt gets disallowed.

-- 
[tim at localhost ~]$ uname -r
2.6.27.25-78.2.56.fc9.i686

Don't send private replies to my address, the mailbox is ignored.  I
read messages from the public lists.