How do I eliminate duplicate emails.

[Chuck Amadi]

I'm trying to stop duplicate emails being delivered to addresses 
contained multiple times in expanded recipient aliases.

e.g. As an example, my virtual might contain:

   fred at mydomain.com    list1 at mydomain.com
   fred at mydomain.com    list2 at mydomain.com
   fred at mydomain.com    list3 at mydomain.com
   fred at mydomain.com    list4 at mydomain.com

When a single email is sent to our Postfix server with two or more of 
these 4 addresses, two copies are delivered. The other two copies are 
ignored by the LMTP service with two warnings in /var/log/messages like:

   May  3 13:00:00 myserver lmtpd[28698]: dupelim: eliminated duplicate 
message to user.fred id <01c101c78d83$a4b6e3f0$0201a8c0 at IVVAIO> (delivery)
   May  3 13:00:01 myserver lmtpd[28698]: dupelim: eliminated duplicate 
message to user.fred id <01c101c78d83$a4b6e3f0$0201a8c0 at IVVAIO> (delivery)


In /etc/imapd.conf I have:

   duplicatesuppression: yes

Which I realize is a Cyrus IMAP feature rather than an explicit Postfix 
feature. Is there any way to eliminate the extra copy so only one is 
actually delivered, either in Postfix's or Cyrus' configuration?
I've tried a huge duplicate_filter_limit in Postfix's main.cf too and 
restarted Postfix, but this didn't deal with the issue:

   duplicate_filter_limit = 20000

Top brass don't like having multiple copies of the same message to deal 
with.

Any assistance would be greatly appreciated,

Cheers

-- 
Chuck Amadi
ROK Corporation Limited
Ty ROK,
Dyffryn Business Park,
Llantwit Major Road,
Llandow,
Vale Of Glamorgan.
CF71 7PY
 
Tel: 01446 795 839
Fax: 01446 794 994
International Tel:   +44 1446 795 839

email: chuck.amadi at rokcorp.com

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