MailScanner slowwing down

G. Armour Van Horn vanhorn at
Thu Apr 30 21:59:51 IST 2009

I was looking at those yesterday because I was running the load average 
up to 10 or 12 in spurts. My box has a Sempron 2200 and a gig of RAM, so 
it does swap when it gets busy. I can upgrade to a machine that's half 
again faster with twice the memory for the same monthly fee, but I'd 
have to run both during the transition and it would take a ton of time 
to move everything over. (It's a webserver for a couple of dozen domains 
and my secondary name server.)

I told Sendmail to stop accepting connections at load average of 6, 
which kept the load average from trying to get to 50. (Yes, I have seen 
the la go that high, although not on this system. It ain't pretty!)

I dropped the child count from five to three, which seemed to help - 
each child just took bigger bites and the throughput didn't seem to be 

One thing that looked appealing was setting up a caching nameserver, but 
all the docs I ran into assumed that you weren't already running BIND on 
the box and that you wanted to cache your local network, so I was too 
confused to get that running. (I do have everything installed, just need 
to figure out the config.)

I did add pause-greet to the Sendmail config, it blocked at least a 
hundred messages overnight. Not a big change, but the price is right.

I'm thinking about setting up greylisting, it will cut down on the MS 
load and should spread out the surges a little.

I guess I should have expected things to slow down when I leapfrogged so 
many versions on Tuesday. Now I've got to figure out how to get it back 
in control or bite the bullet and get some more horsepower.


Martin Hepworth wrote:
> See
> and
> Dropping unknown recipients and having a local caching nameserver are 
> generally the first things to sort, then look at the number of 
> children and batch size...
> -- 
> Martin Hepworth
> Oxford, UK
> 2009/4/30 Mail Admin <mailadmin at 
> <mailto:mailadmin at>>
>     Hi All,
>     Recently I am finding that the amount of incoming mail through my
>     MailScanner Server  is really slowing down things.  There is a
>     heavy load now since I took on a domain that seems to me well
>     spammed. Yesterdays processing processed 22,000 emails @88% Spam
>     approx.
>     Server Spec POWEREDGE 1850 XEON 2.8GHZ/2MB 800FSB – WITH 2 GIG RAM
>     and RAID 1  Configuration on two Disks RPM 10K… Its Running Fedora
>     Core 5, Send Mail 8.13.8-1.fc5 with MailScanner 4.69.7-1 with SA,
>     Razor, DCC., MailWatch V1
>     Its working very well blocking spam, but only in the last couple
>     of days its got really slow.
>     Any ideas on how to reduce the load on this server>? By blocking
>     mail at the MTA before it hits MS? OR Tweaking my processes?
>     What do the Experts think on the Server Spec, for the amount of
>     traffic?
>     I’d appreciate any help
>     Regards
>     Kevin
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