How do I know when Mj finishes a message?

[bill @ ecology . bio . dfo . ca (Bill Silvert)]

I sometimes have to send out administrative messages to several lists at
once. Since lots of subscribers are on more than one list, I run sort -u
to create a one-time list for the message. Since I want to erase the list
afterwards, I need to know when Mj is through reading it. How do I do
that?

-- 
Bill Silvert, Habitat Ecology Section, Bedford Institute of Oceanography,
P. O. Box 1006, Dartmouth, Nova Scotia, CANADA B2Y 4A2, Tel. (902)426-1577