interesting mail delivery problem   

I have an interesting, intermitent, problem with Exchange 2000 (SP3 and 
Post-SP3 rollup installed) running on Windows 2000 (SP4 and current updates). 
 Mail comes in addressed to non-existant users (i.e.qwertyuiop@domain.com) 
and goes randomly to users mailboxes.  Not all non-existant user email comes 
through, and it is not consistent who gets it.  This started with one user 
getting three to five a day, now it is several hundred coming in.  In 
addition, just to make things interesting, when users on the server send each 
other mail, sometimes but not always it will be recieved by several, even 
all, of the users in addition to the user is it addressed to.  Again, not 
every message, and not the same folks recieving it.  I am at a complete loss! 
 Does anyone have any good ideas?

date: Tue, 22 Mar 2005 08:17:01 -0800   author:   Chris Harrison, Certified Nets Chris Harrison, Certified

Re: interesting mail delivery problem   

This is pretty typical of Spam Mail.  If you open the Internet Header on the 
spam messges you should see your users smtp address somewhere in the header. 
Spammers also use Dictionary Attacks to send mail to any address @ 
yourcompany with any name or character to see if they can hit a legitimate 
address.  Meanwhile your Exchange server is sending back NDR's to these 
non-existent users which can fill up your Bad Mail Folder and Message 
Queues.  Your only option at this point is purchase a Third Party 
AntiSpamming Product which you did not mention in your post if you currently 
have one or two.  You should also consider writing a simple batch file for 
cleaning your Bad Mail directory daily or weekly.   Not sure what your issue 
may be in regards to your internal users sending mail to each other.  Any 
NDR received back from the user if it does not go through?

-- 
John Oliver, Jr.
MCSE, MCT, CCNA, Exchange MVP
Microsoft Certified Partner

"Chris Harrison, Certified Nets" <Chris Harrison, Certified 
Nets@discussions.microsoft.com> wrote in message 
news:B4B6BCB9-630A-4A85-A339-8317A2C54C96@microsoft.com...
>I have an interesting, intermitent, problem with Exchange 2000 (SP3 and
> Post-SP3 rollup installed) running on Windows 2000 (SP4 and current 
> updates).
> Mail comes in addressed to non-existant users (i.e.qwertyuiop@domain.com)
> and goes randomly to users mailboxes.  Not all non-existant user email 
> comes
> through, and it is not consistent who gets it.  This started with one user
> getting three to five a day, now it is several hundred coming in.  In
> addition, just to make things interesting, when users on the server send 
> each
> other mail, sometimes but not always it will be recieved by several, even
> all, of the users in addition to the user is it addressed to.  Again, not
> every message, and not the same folks recieving it.  I am at a complete 
> loss!
> Does anyone have any good ideas?

date: Tue, 22 Mar 2005 16:08:58 -0500   author:   John Oliver, Jr. [MVP]