A duplicate posting occurs when one person attempts to post
a seemingly identical message to the same mailing list, more than once in one
day.
Lyris looks at the first 200
characters to determine if a posting appears to be a duplicate. The reason for
this is that some "automatic answer" programs (such as the
"vacation" program) will automatically reply to anything they receive
by adding a "I'm on vacation" sentence to the top of the message, and
quote the rest of the message. Lyris will catch the duplicate posting, since
the top of the message will be identical.
Normally, duplicate postings are
the result of the author not being careful, and sending the same message twice,
or of some Internet mail error, where the same message is delivered twice.
By default, Lyris rejects duplicate
postings. Normally, you will want to leave this default setting as it is, since
there usually is no good reason why your list members would want to receive the
same message twice. Also, this feature is quite effective as a mail-loop
prevention technique, when people attach a misbehaving "automatic email
answering" program to their email address. Most "vacation"
programs are well behaved, and do not answer list-mail (they detect the
"Precendence: bulk" message header). However, people sometimes decide
to write their own "vacation" program, or other automatic email
generating program, and thus can cause problems on a list. This feature takes
care of this problem.