Sendmail / Email copy - Fixed

Jeff Vian jvian10 at charter.net
Thu Mar 18 02:32:09 UTC 2004



Alexander Dalloz wrote:

>Am Mi, den 17.03.2004 schrieb admin at kclinux.net um 21:57:
>  
>
>>After playing around, I changed the line for this account:
>>emergency: SPRINT-PCS-EMAIL,SPRINT-PCS-EMAIL,SPRINT-PCS-EMAIL,PAGER-NUMER
>>to this:
>>emergency:
>>SPRINT-PCS-EMAIL,SPRINT-PCS-EMAIL,SPRINT-PCS-EMAIL,PAGER-NUMER,emergency
>>    
>>
>
>Be careful! As Tom already said you made a loop. The line above have to
>be:
>
>emergency:
>\emergeny,SPRINT-PCS-EMAIL,SPRINT-PCS-EMAIL,SPRINT-PCS-EMAIL,PAGER-NUMER
>
>  
>
IIRC, at some time in the past, the syntax as he put it did, in fact, 
cause loops and cause sendmail to barf. At that time the "\" was 
*required* to prevent loops.  This was a major problem with sendmail and 
inexperienced administrators at that time.  However, that was changed 
(several years ago) as a result.  The sendmail system recognizes when a 
loop would occur and thus takes this syntax as instruction to deliver to 
the actual account as well as to the listed aliases and does not 
repeatedly expand the loop.  In fact it intelligently parses the list 
and if it contains multiple instances of the same address it only 
delivers one copy.

I have used this for considerable time to deliver mail coming to a 
single account to multiple addresses as well as the original account. 
 One example is mail coming in for an administrator account that needs 
to have multiple recepients, the way he used it.  Another example that 
is helped by the fixes for sendmail was the use of multiple alias groups 
for selectively delivering mail to subsets of the list.  Realisticly one 
person could be in multiple of the groups. Sending mail to several 
subsets before the fixes that user would have gotten multiple copies of 
the mail but since the fix they only get one regardless of how many 
times they appear in the composit list.

Although your syntax is technically the correct one, but it will work 
perfectly without the "\".


>To explain:
>
>localuser:    \localuser, userb, userc
>
>This will deliver the mail to the LHS recipient and copies to userb and
>userc without causing a loop for the LHS.
>
>  
>
>>Adding the emergency to the end of the line got the emails going back to the
>>local account, and it's now going to all the PCS phones and pager.
>>
>>    
>>
>  
>





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