Milter-greylist

> Would it be helpful to limit the sendmail processes by
> e.g. MaxDaemonChildren?
> 
It may make sense if your system resources are limited, especially CPU
and memory.
It is better to continue serving the already established connections,
than allowing a lot of connections and no progress on them.
If you have to do artificial limit, it is better to put at the earliest
stage, so MaxDaemonChildren is a good candidate. I am doing this on
small Tru64 UNIX servers dates back to 1993 with 128 Mbyte of RAM, and 
175 MHz CPU.
If you use MaxDaemonChildren restriction do not forget to tune different
SMTP connection timeout values, since hanging connections may make
your server unusable.

Bests,
Attila