[ale] Maillog: User unknown

[Tony Carter]

>>	I noticed something interesting in my maillog file today, there are
thousands of entries like below, I spent a few minutes googleing and could
find any good info.  Does anyone know whats happening here?  The mail server
has about 20 accounts and 2 domains, 'mydomain1' and 'mydomain2'. 
	
>>	Nick
		
>>	Dec 27 11:21:05 mydomain1 sendmail[21756]: jBRGL50G021756:
<hrs at mydomain2.com>... User unknown
>>	Dec 27 11:21:06 mydomain1 sendmail[21756]: jBRGL50G021756: < 

Looks like someone is enumerating usernames to possibly use for relaying
(spam) mail??  Sorry I don't know sendmail but does this message indicate
that the attempts are made from the sendmail host itself? If so, you should
make sure that you don't have a cgi script that allow mail relaying..
 
-Tony