On Tue, Sep 21, 2010 at 02:18:32PM -0500, Jay G. Scott wrote:
> i just swapped postfix in for sendmail on a mail server.
> are there any metrics i can get to show why postfix is better?
[ Sendmail probably evolved in some respects since I've last looked
at it closely. The below may be somewhat dated. ]
Unlike Sendmail, Postfix does not stop delivering mail under load.
Deferring load may make sense on a compute server that occasionally
sends email, but makes no sense on a mail server, as the congestion only
gets worse. So the main difference is that Postfix has nothing quite so
ineffective as QueueLA and RefuseLA.
Postfix is more I/O efficient, because the single queue file format
requires just one fsync per message, rather than two. Delivery of the
same message to multiple next-hop destinations proceeds in parallel,
in Sendmail the queue-file is locked for serial delivery.
The Postfix queue-manager makes it possible to do connection caching
right, and to manage destination concurrency limits.
Finally, you get configuration files humans can read, and source code
good programmers can enjoy reading. Good documentation, better logging,
and a better security track record.
This said, if Sendmail works for you, by all means, use it. The monolithic
design makes some very specialized requirements easier to meet. There
have not been announcements of major security issues for a few years.
--
Viktor.
