I am sending an email to three distribution lists (using Outlook 2003). Some
of the members in these DLs overlap, so if I compose a single message that
will go to each of the three lists, some members are listed more than once.
If the recipients names appears more than once in the "To:" box or "Bcc:"
box, is it possible they will receive multiple copies of the email? Or will
Outlook recognize the duplicates and send each recipient only one copy?
I want each contact to receive only one email - what should I do?
Yes, it's very possible unless your mail server does some filtering of duplicate addresses. Outlook does no such filtering.
Yet another reason why DLs are cumbersome. If you had all these people in a folder with a different category for each of the three "lists," you could use a filtered view to perform a mail merge with them to generate individual email messages.

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Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I am sending an email to three distribution lists (using Outlook 2003). Some
> of the members in these DLs overlap, so if I compose a single message that
[quoted text clipped - 5 lines]
>
> I want each contact to receive only one email - what should I do?
Chuck Morrobeo - 17 Mar 2006 23:20 GMT
Thanks for your quick reply.
My server administrator said he doesn't know of any filters on our email
server. Yet when I did a test and used Outlook 2003 (my work account) to
email some alternate accounts, I didn't receive any duplicates at those
accounts. So the additional addresses got chopped out somehow and no
duplicates were sent. I'm assuming, though, that this isn't a sure way to
know that all the addresses I use will get the same treatment, i.e. if I
accidentally list them twice in the To: box. Or maybe it is?
> Yes, it's very possible unless your mail server does some filtering of duplicate addresses. Outlook does no such filtering.
>
[quoted text clipped - 9 lines]
> >
> > I want each contact to receive only one email - what should I do?
Sue Mosher [MVP-Outlook] - 17 Mar 2006 23:36 GMT
It's up to the server, which is a black box as far as you're concerned. Only you can decide whether to rely on the results of your testing.

Signature
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
> Thanks for your quick reply.
>
[quoted text clipped - 9 lines]
>>
>> Yet another reason why DLs are cumbersome. If you had all these people in a folder with a different category for each of the three "lists," you could use a filtered view to perform a mail merge with them to generate individual email messages.
>> >I am sending an email to three distribution lists (using Outlook 2003). Some
>> > of the members in these DLs overlap, so if I compose a single message that
[quoted text clipped - 5 lines]
>> >
>> > I want each contact to receive only one email - what should I do?
Brian Tillman - 18 Mar 2006 22:28 GMT
> Yes, it's very possible unless your mail server does some filtering
> of duplicate addresses. Outlook does no such filtering.
I just tried it with two DLs each containing the same address. I put one in
the To and one in the Cc. The recipient received only one copy and his
address did NOT apper in the Cc. So, either Outlook checked and did not
send the redundant message or the Exchange server did.

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Brian Tillman
Richard Poon - 20 Mar 2008 15:11 GMT
If you use Exchange Server at the back end, it will eliminate duplicate
addresses from multiple DLs to send a message.
Richard
> > Yes, it's very possible unless your mail server does some filtering
> > of duplicate addresses. Outlook does no such filtering.
[quoted text clipped - 3 lines]
> address did NOT apper in the Cc. So, either Outlook checked and did not
> send the redundant message or the Exchange server did.