[Techtalk] sendmail configuration -> rejects for unknown user

[Rudy Zijlstra]

Conor Daly wrote:

>On Mon, Nov 20, 2006 at 02:55:17PM +0100 or thereabouts, Rudy Zijlstra wrote:
>  
>
>>What i would like to do, is teach sendmail to check whether the local 
>>recipient exists, and refuse if not. I know it is possible, but after 
>>several hours of searching i still have not been able to find how to do 
>>it. Can anybody give me some pointers  on this one?
>>    
>>
>
>It can probably be done with sendmail but, what I did was install exim and
>use the eximconfig package at http://www.jcdigita.com/eximconfig .  This
>does lots of SMTP filtering for stuff like unknown users, misconfigured
>connecting servers (most spam bots do only the sending bit, not receiving)
>and more .  It also does grey-listing where a message is temporarily
>rejected and accepted if it is resent within a certain time window.
>
>It's almost set and forget though I did have to do some tweaking after it
>rejected some valid senders...
>
>Conor
>  
>
Late in the night i found the solution, using the virtuser table in 
sendmail, example entries:

webmaster at another-site.com   webmasters
@another-site.com            marc
sales at my-site.com             sales at another-site.com
paul at my-site.com              paul
finance at my-site.com           paul
@my-site.com                  error:nouser User unknown

Its the last one that is important, taking care that unknowns are rejected. 

Rudy