From Elendor
Syntax: +REPLY[/FULL] [@<altname>] [<bboard name>] <message>
This command replies to a message from your mailbox or on a bulletin board. If
the message is on a bulletin board, your reply will be addressed to that
bulletin board. If it is a mail message in your mailbox then it will be
addressed to the sender and all addressees (except you) of the original
message. If the /FULL switch is supplied, your reply will instead be
addressed to _everyone_ who received the original message (not just the
bulletin board if it is a bulletin board posting and not omitting you if
it is a message in your mailbox). The subject line will be set to "Re: the
original message's subject line". See HELP mail editing for how to change
the address and/or subject line once +reply has been executed.
Example1: +reply 5
(Starts a message in reply to message 5 in your mailbox.)
Example2: +reply public 3
(Starts a message in reply to the public bulletin board's third posting.)