Because my directory server is running on quite old hardware (K6-2, 256M RAM), and it is faily loaded already, I wondered if changing the MTA might help. I use Debian, and I’ve never changed the MTA on it, so it currently has Exim.
The system doesn’t process much mail, mainly just local mail and spam, so I’m not conerned about scalability. I did some digging on Google, and found a great comparison between Unix MTA’s. It might for an enlightening read. I also found a forum thread talking about the scalablity of Exim, and I have to say that guy has a sweet server setup, with his MTA’s PXE booting and installing automagically…it’s just like Active Directory! 
Anyway back to it. I couldn’t find any conclusive measurements, or even vague measurements, of the resource usage between the two programs. I happen to have another server that doesn’t process any mail and runs Postfix, so I thought I’d just take a peek at the memory usage of the two. It looks like Postfix runs separate programs for the queue management and the program itself, and it weighs in at about 2.5MB of memory. Exim has a single process and weighs in at about 450k.
Quite a difference. There wasn’t much point in looking at the CPU load – it’s 0 because neither of them are processing any mail 
I think I’ll stick with Exim on my directory server though. Lower memory footprint = better at the moment.
To start, allow me to point out that your internet site is fantastic. I love the theme that you have. It was very easy on the eyes. Appreciate your article too. Definitely subscribed to your feed to make sure I won’t be missing out on any updates. Excellent job! Toast to a productive business
Thanks Verla! The theme is actually just one of the old default WP themes, but yes, I chose it because it is easy on the eyes