Ordinarily, when mailstats produces its output,
it prints the human-readable names of the delivery agents in its
rightmost column:
% mailstats
Statistics from Sat Jan 1 17:30:02 2000
M msgsfr bytes_from msgsto bytes_to msgsrej msgsdis Mailer
0 0 0K 246 685K 0 0 prog
... 
here
If you prefer to omit delivery agent names, you can suppress the last
column with this -o command-line switch:
% mailstats -o
Statistics from Sat Jan 1 17:30:02 2000
M msgsfr bytes_from msgsto bytes_to msgsrej msgsdis
0 0 0K 246 685K 0 0
...
gone
Note that this -o switch can be combined with the
-p switch (described next) to also suppress
printing the M line in that output.
