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List:       majordomo-users
Subject:    Re: Multiple messages
From:       Chip Old <fold () bcpl ! net>
Date:       2002-04-29 12:15:27
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On Sun, 28 Apr 2002, Chip Old wrote to Majordomo Users:

> [Re CheckpointInterval] I don't remember whether commenting it out in
> the cf file sets it to the default value or disables it completely.  I
> need to check the bat book, which I'll try to remember to do on Monday.

Here's what the bat book says:

"When a single email is sent to many recipients (those on a mailing list,
for example), a single sendmail process handles all recipients.  Should
that sendmail process die or be killed halfway through processing, there
is no record that the first half was delivered.  As a result, when the
queue is later reprocessed, the recipients in that first half will receive
the message a second time.

Thew CheckpointInterval (C) option can limit this duplication.  It tells
sendmail to rewrite (checkpoint) its qf file (the file that contains the
list of recipients) after each group of aq specified number of recipients
has been delivered.  Recipients who have already received mail are deleted
from the list, and that list is rewritten to the qf file."

As I mentioned in an earlier message, the cf file line reads
"O CheckpointInterval=num" where num is a numeric value.  If that value
is missing or zero, CheckpointInterval is disabled.  If the entire
CheckPoint interval option is missing from the cf file (or commented out),
it defaults to 10.

The bat book  goes on to say that there is a small performance penalty
that increases as num approaches 1 (because the lower the
CheckpointInterval value, the more often sendmail has to interrupt
processing the queue to rewrite the qf file).  A good starting value is 4,
meaning that at most 4 people will receive duplicate deliveries.

So, if CheckpointInterval is commented out in your cf file (isn't that
what you said?) then your sendmail will use a CheckpointInterval value of
10, meaning that at most 10 recipients will get duplicate messages if
sendmail is interrupted while processing delivery to one of your lists.
If more recipients than 10 are receiving dups, then somet=hing else is
wrong.

-- 
Chip Old (Francis E. Old)             E-Mail:  fold@bcpl.net
Manager, BCPL Network Services        Phone:   410-887-6180
Manager, BCPL.NET Internet Services   FAX:     410-887-2091
320 York Road
Towson, MD 21204  USA


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