Why does 4.1BSD leave mail processes around?

[govern at houxf.UUCP]

Fairly often, when I do a ps -gaxu to find out what my system is doing,
I see a pair of processes in the IW state that appear to be spawned
by Mail:
	send-mail -i someuser
	...local%mail -d someuser

I don't know what they're waiting for, but they tend to hang around
for a while.  I also tend to have at least one zombie owned by root,
which is in the "<exiting>" state, and I can't kill it.

Does anyone know why these are there, and how (or whether) to
prevent them?
		Thanks,
				Bill Stewart
				houxf!govern
				houxf!hoscf!bin <-- Better