[GRLUG] Sendmail as secondary (backup) MX

[Luke Stroven]

I use the virtusertable as well like this:

emailuser at realdomain.com emailuser at internalservername.com

I add an entry for each user, and then at the end of the virtusertable,
I do a:

@realdomain.com    error:nouser 550 EMAIL ADDY DOES NOT EXIST. CHECK
YOUR SPELLING

This way all email to non existent users gets rejected immediately.

-Luke

On Tue, 2006-10-31 at 10:36 -0500, Benjamin Eavey wrote:
> Has anyone set this up and worked out all the kinks?  I have a machine 
> running Sendmail and acting as a backup MX for several domains. 
> Everything has been working fine, for the most part, but now I'm running 
> into problems with the queue becoming overloaded.
> 
> It looks like a bunch of spam, and it appears to be a bunch of "550 - 
> undeliverable" messages and other similar stuff.  Looks like the 
> spammers are sending to non-existent addresses at the domains I host, 
> which are then bouncing with "undeliverable" messages, which are then 
> building up on my sendmail server, which is trying to deliver them to 
> the spoofed originating email addresses.
> 
> I know this is bad, and I'm pulling my hair trying to figure out how to 
> make this work properly, but I'm not getting anywhere.
> 
> Can anyone offer any suggestions?  Am I explaining this well enough that 
> the problem makes sense?
> 
> Thanks,
> 
> -Ben
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