MailScanner + Exim

[gal3ler]

Hi,

We're currently using Chirpy's MailScanner + Exim for our outgoing mail gateway. I was wondering if anyone had any good settings for Exim + MailScanner for a very busy server. The server is:

Dual Xeon 2.4Ghz
4GB RAM
RHEL 4

MailScanner is just having a hard time keeping up with scanning all of the incoming messages and I was wondering if there's a way to increase it's performance along with Exim to have them handle more messages.

[sawbuck]

Might be worth a read of the optimization info listed here:
http://wiki.mailscanner.info/doku.php?id=maq:index

[chirpy]

A couple of things to get you started:

1. Use the dictionary attack ACL and make sure all :blackhole: are changed to :fail: in /etc/valiases/*

2. If you get a lot of RBL hits, it might be a good idea to offload RBL rejection directly into an exim ACL rather than having MailScanner do it

3. Run a local caching DNS server if you aren't already and be sure that it is the first listed nameserver IP address (i.e. that of your server) at the top of /etc/resolv.conf

4. Reducing the number of children down to 2 in MailScanner.conf can help with load, but can adversely affect the speed of delivery if a queue builds up

[gal3ler]

Yeah right now the children is set to 20 heh

Lots of email going through this test gateway.

How do these look:

Max Children = 20
Queue Scan Interval = 6


Max Unscanned Bytes Per Scan = 1000000
Max Unsafe Bytes Per Scan = 500000
Max Unscanned Messages Per Scan = 90
Max Unsafe Messages Per Scan = 5


Max Normal Queue Size = 1500

[chirpy]

I would suggest 20 is way too high. I would never set it above 5 and then only on a 4GB server. 3 is usually perfectly sufficient for most web server usage.