mailq holding large jobs

[YATES, JOHN H.]

It appears that mailq holds large jobs for delivery overnight.
I don't see any docs on this in the sendmail man page or in
the communications manual. I am at IRIX 3.3.1, I didn't notice
this behavior at 3.3 , but just may not have noticed.
Is my observation correct? If so, how do I disable it so all
jobs get processed right away?
Thanks, John
yates at c.chem.upenn.edu