Mail vs. response time

[George Gonzalez]

Thanks to everyone who answered my question about A/UX mail file permissions.
Special thanks to Donald L. Nash who had the definitive analysis and patch.

Now another mail-related question:  On our system, we often send mail to
25 people at a time.  Whenever we do this, it brings the system to its knees.
Terminal response time becomes intolerable,  it can take 45 seconds to do 
a trivial command.

Is there an easy way to lower the priority of mailx (or send-mail?).
I don't mind delaying the mail by a few minutes if it restores good 
terminal response time.

Any ideas?