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Re: How to never see dupes again (was: someone at - dups)

  • From: John A. Tamplin
  • Date: Thu Mar 18 11:28:56 1999

On Thu, 18 Mar 1999, Stephen Sprunk wrote:

> Sick of misconfigured majordomos, incessant cross-posters, and occaisional
> operator error?
> Put in .procmailrc:
> # Use a cache of Message IDs received to avoid duplicate messages
> # (i.e. same message posted to two [or more] mailing lists will be
> # delivered only once [to first matching procmail rule.)
> :0 Wh:.msgid.cache.lock
> | formail -D 8192 .msgid.cache

Beware that while Message IDs are supposed to be unique, some clients do not
actually guarantee uniqueness.  We run the Cyrus local delivery agent, and 
used to have it configured to drop duplicate message IDs.  However, we had
complaints from customers not getting their email from certain people and 
upon investigation we found that the Message IDs were being reused.  So, we
reluctantly disabled this feature.  Those mail clients may have been updated
by now, but I am certain that some remain.

Also, much of the time I see duplicates on mailing lists they get new 
message IDs as they pass through the list mechanism so it wouldn't help 
you anyway in those cases.

John A. Tamplin					Traveller Information Services
[email protected]				2104 West Ferry Way
256/705-7007 - FAX 256/705-7100 		Huntsville, AL 35801