[TriLUG] order of operations (sort of) for sendmail

[Aaron S. Joyner]

Brian Henning wrote:

> Hi!
>   Would someone mind telling me quickly if procmail processing comes 
> before sendmail rejects based on whether a mailbox exists (my instinct 
> says no...)?  

Procmail happens *after* sendmail has done everything it's ever going to 
do.  When it's finished, it washes it's hands of the message by handing 
it off to Procmail, with a note saying "put it in <suzie's> box".  
Procmail is the "local delivery agent", sendmail is the "mail transport 
agent", after the message is done being transported around, it gets 
locally delivered.

> I want to create a no-reply at mydomain.com that gets /dev/null-ed 
> (rather than causing a bounce to the sender)..  Can I do this with an 
> alias?  

Yes.  The right way to do this is in the aliases file.  Simply create an 
address, and assign it's output to a file, /dev/null.  An entry like 
this in your aliases file will do the trick:
no-reply     /dev/null

Keep in mind of course that will create that address for all mail 
domains hosted on the server in question.

> Or a procmail recipe?  Or do I absolutely have to create a new mailbox?

That will work, but it's not quite as elegant a solution.  Also don't 
forget that depending on how you're doing spam / virus scanning, the 
mail to this address may go through that processor-intensive filter.  So 
if you're throwing a lot of mail into this alias, you might want to 
whitelist it for spam and virus filtering through what ever mechanism is 
appropriate, if possible.

Aaron S. Joyner