[courier-users] annoying dictionary spammers

[Scott]

At the moment one of my mail servers is being bombarded with delivery 
attempts to unknown users at the rate of thousands every minute 
([EMAIL PROTECTED] [EMAIL PROTECTED] etc).  Courier is faithfully denying 
them with 550 User Unknown errors.  I've extracted all the connecting IPs 
from maillog and have found over 100,000 unique IPs!  Some of them are from 
huge ranges of class A addresses.  This is the first time I've had this 
happen and I wonder two things:

1. Who/what is doing this?
2. What can I do to block this behavior.
I started making firewall rules, but then realized blocking that much traffic 
might block legitimate traffic too.  At least courier is doing a good job 
keeping the load very low on this poor little P3-866MHz with only 256MB RAM. 
 Hooray for that anyway.

-Scott



-------------------------------------------------------
SF.Net is sponsored by: Speed Start Your Linux Apps Now.
Build and deploy apps & Web services for Linux with
a free DVD software kit from IBM. Click Now!
http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click
_______________________________________________
courier-users mailing list
[EMAIL PROTECTED]
Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users