SASL AUTH dictionary attacks

[Forrest]

I recently updated my system from Sendmail to Postfix 3.0.1.  Since that 
time, I've been targeted with several SASL dictionary attacks; activity 
I've not seen in this number before.

Reading around elsewhere, I wonder if the script kiddies are looking for 
Postfix in the banner (which I've since removed), going after a presumed 
vulnerability?

I've seen items like Fail2Ban and so forth.   I don't know that it would 
be appropriate for Postfix to temporarily ban IPs or throttle these 
types of failures.   There may be some settings I've not yet become 
aware of that I could tweak to either discourage this or make it very 
difficult.


Thanks.