Vacation/out of office message was not delivered to a listserv
The listserv program treats messages with certain words or phrases in the subject line as possible automatic messages. These suspected automated messages will be bounced back to the list owner as a rejected message, instead of being sent to the listserv subscribers.
If your subject line contains "on vacation," for example, the listserv will reject this posting and not send the email to the listserv subscribers or add it to the message archive. Other phrases that will be rejected include "out of the office" and "out of town."
The listserv rejects emails with these phrases in the subject line to avoid causing an email loop. For example, if you have an auto-reply set up on your email account and you receive a message from one of the listservs you are subscribed to, your auto-reply or out of office message will get sent out to the entire listserv. If the listserv is configured so that you receive a copy of your own posts, it will send you a copy and trigger another auto-reply message, which will get delivered to you by the listserv, prompting another auto-reply message, ad infinitum.
You can still send a vacation message to a list, as long as you do not use one of the rejected phrases in your subject line. Some possible subject lines that will work and get the idea across include:
Subject: Not here next week
Subject: Vac days 8/14-8/18; returning 8/21
Subject: Gone 8/14-8/18
Of course you do not want to use these subject lines when setting up your auto-reply message, since it will cause an email loop.