List owners may occasionally see a message BOUNCE: 

Date: Fri, 30 Oct 1998 16:57:08 -0800 (PST)
From: owner-histlit@lists.uoregon.edu
Subject: BOUNCE histlit@lists.uoregon.edu:     Admin request of type
 /\bsubscribe\b/i at line 7
To: owner-histlit@lists.uoregon.edu

The most common cause for this is the use of Majordomo command words
in the first 20 lines of a message (in the case above that word was
subscribe). Majordomo attempts to protect the entire list membership
from misdirected command requests by bouncing anything suspicious to
the list owner for approval or re-direction.

You can see the list of "forbidden" words here:

http://darkwing.uoregon.edu/~llynch/majordomo/obscure-words.html

and the details of how to approve a message and send it back to the
list here:

http://cc.uoregon.edu/mailinglists/mod.html