From Elendor
Syntax: +DELETE[/FORCE] [@<altname>] <messages>
This command marks the indicated messages for deletion. <messages> can just be
a message number or you can use any of the many extended formats described
in HELP MESSAGES. Once you have all the messages you want to delete marked
for deletion you can use the +CLEAR command to actually delete them (see
HELP +CLEAR). If you change your mind, you can use the +undelete command
to unmark messages previously marked for deletion (see HELP +UNDELETE).
Unless you supply the optional /FORCE switch, +DELETE will not mark
messages that are unread.
Example: +DELETE 1 3 10-14 25
(Marks messages 1, 3, 10, 11, 12, 13, 14, and 25 for deletion.)
