New mail blocks result of Ralsky's latest attacks?

["Bob German" <bobgerman () irides com>]

A colleague informed me this morning that Alan Ralsky is doing
widespread bruteforce attacks on SMTP AUTH, and they are succeeding,
mainly because it's quick, painless (for him), and servers and IDS
signatures don't generally offer protection against them.
 
Could this be why everyone's locking up their mail servers all of a
sudden?
 
Does anyone know of a way to stop them?
 
Bob