Don't use POP3. Having Outlook setup with the Exchange Server service and
an Internet E-mail service both pointed at the same Exchange Server mailbox
is an unsupported combination and duplicate emails are a VERY common side
effect.

http://support.microsoft.com/?kbid=245446
XCLN: Error Message: No Transport Provider Was Available
(You Cannot Use the Exchange Server and Internet E-mail Services in the Same
Profile)

A very simple solution is to use IMAP instead. Exchange servers do IMAP
very well, this type account leaves all mail on the server so its available
from anywhere, and you don't get duplicates.

Hal
--
Hal Hostetler, CPBE --
Senior Engineer/MIS -- MS MVP-Print/Imaging -- WA7BGX
http://www.kvoa.com -- "When News breaks, we fix it!"
KVOA Television, Tucson, AZ. NBC Channel 4
Still Cadillacin' - www.badnewsbluesband.com

"
wrote in message ...
Hi,

Does someone know why, when you use pop3 account with a mailbox on an
Exchange Server, the mails are downloaded twice from the server ? but only
if
the option "Leave a copy of message ont he server" is check (in the tab
"Advanced")

How to avoid that without to uncheck the option "Leave a copy of message
ont
he server".

Thanks