[TriLUG] sendmail vs. postfix - was Re: stupid sendmail question?

[Aaron S. Joyner]

Jason Tower wrote:

>in my experience postfix's more modular nature means that additional 
>functionality can be added on relatively easily.  for example, postfix 
>2.1 includes the "verify" feature which enables it to see if a message 
>is deliverable *before* the smtp data is accepted - if not, it returns 
>a 550 to the sender.  no bounces, nothing gets queued.  this is 
>incredibly useful when using postfix as a gateway, often in conjunction 
>with amavis/spamassassin/clamav/etc.
>
>jason
>  
>
Just to throw more information on the fire, erm... umm...  anyway...

The verify feature (straight from the man page):

>*BUGS*
>       The  address  verification  service  is  suitable only for
>       sites that handle a low mail volume.  Verification  probes
>       add  additional  traffic  to  the  mail  queue and perform
>       poorly under high load.  Servers may blacklist sites  that
>       probe excessively, or that probe excessively for non-exis-
>       tent recipient addresses.
>
>       If the persistent database ever gets  corrupted  then  the
>       world  comes  to  an end and human intervention is needed.
>       This violates a basic Postfix principle.
>
Venema is often overly-cautious, especially with new features, and it 
may not be so bad after all.  Personally, I'm interested in playing with 
the feature, and I've been setting up a test box earlier today for 
precisely that purpose.  But you have to admit, the warning is a bit 
dire.  :)

But again, on the flip side, have you tried using Sendmail to query a 
mysql database for it's alias entries?  Don't.  :)  Stick with Postfix 
for tasks such as that.  It's easy to setup, and works remarkably well.  
The only catch being it does open one database connection for every 
query, so it's not the world's most efficient implementation, but mysql 
and the mysql client libraries are fast enough that it doesn't really 
matter.  Just note that in large installations you have to kick your 
max_connections for mysqld (700 or so should be fine), os file 
descriptors, and a few other things through the roof.  :)

Aaron S. Joyner