[Mimedefang] New spam technique

[David F. Skoll]

On Fri, 2 Jul 2004, Penelope Fudd wrote:

> Recently spammers verified their mailing list using this SMTP dialogue.

This is an old technique called a "dictionary attack" or "directory
harvesting".

Sendmail 8.13 has countermeasures, like closing a connection after N bad
SMTP commands.

I run a script from cron that parses the mail log and firewalls off directory
harvesters.

--
David.