[cobalt-users] Is this some kind of Denial Of Service Attack

[aljuhani <aljuhani@xxxxxxxxx>]

Hello List.

I have just noticed that someone were trying to relay mail through our server 
and the attempts were more than once from the same IP address.  He was unable 
to relay anything through the server but he managed to generate a sendmail 
error as shown below.  My question is this some type of DoS attack that 
intended to break-into the server or sendmail.

Oct 21 05:08:18 ns sendmail[5350]: g9L96wQ05350: SYSERR: putoutmsg 
(node-c-8235.a2000.nl): error on output channel sending "550 5.7.1 
<devp94g@xxxxxxxxxx>... Relaying denied.  Please check your mail first.": 
Broken pipe.

Thanks

Al-Juhani
aljuhani@xxxxxxxxx