Duplicate emails using pop

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Guest

I was reading kb article 292249 which had the information below.

My question is where or how can i find out what those unique id numbers are.
I had a situaiton where my email server crashed and most of my outlook 2003
clients received duplicate emails in their inbox. Most of my clients have
their outlook client set to leave a copy of the message on the server. the
email was on a raid 5 array, and one of the drives crashed. I rebuilt the
array, and then these problems occurred.

From the article

MORE INFORMATION
When you enable the Leave a copy of messages on the server option and
messages are downloaded, the unique ID numbers of each of those messages is
added to a list of messages previously downloaded so that Outlook does not
re-download the messages during future synchronizations. When the Deleted
Items folder is emptied, Outlook removes the unique ID numbers of the
previously downloaded messages from the list in preparation for deleting the
messages from the server. If a synchronization (either manual or automatic)
begins during this process, Outlook erroneously downloads all of the messages
again because their unique ID numbers do not appear in the list of previously
downloaded messages.
 
BookerW said:
I was reading kb article 292249 which had the information below.

My question is where or how can i find out what those unique id
numbers are.
I had a situaiton where my email server crashed and most of my outlook
2003
clients received duplicate emails in their inbox. Most of my clients
have
their outlook client set to leave a copy of the message on the server.
the
email was on a raid 5 array, and one of the drives crashed. I rebuilt
the
array, and then these problems occurred.

From the article

MORE INFORMATION
When you enable the Leave a copy of messages on the server option and
messages are downloaded, the unique ID numbers of each of those
messages is
added to a list of messages previously downloaded so that Outlook does
not
re-download the messages during future synchronizations. When the
Deleted
Items folder is emptied, Outlook removes the unique ID numbers of the
previously downloaded messages from the list in preparation for
deleting the
messages from the server. If a synchronization (either manual or
automatic)
begins during this process, Outlook erroneously downloads all of the
messages
again because their unique ID numbers do not appear in the list of
previously
downloaded messages.
Click to expand...


For inbound e-mails, the UIDs (unique identifiers) are assigned by the
mail server. When your e-mail client issues the UIDL command, the mail
server responds with a list of mail items and a UID for each. If the
e-mail client doesn't support the UIDL command, or if the mail server
doesn't support it, then the relative index number assigned to each mail
item gets used (from the mail server's output from the LIST command sent
by the e-mail client. The relative index numbering can cause confusion
between different mail sessions because it can get changed and the
e-mail client gets out of sync. You could, for example, end up deleting
the wrong message or trying to yank one that had been deleted by a
different e-mail client connecting to the same mailbox.

For information on how POP3 works, read its RFC 1939
(http://www.cse.ohio-state.edu/cgi-bin/rfc/rfc1939.html). That's where
I figure out how it is supposed to work. If you want to see the UIDs,
you could telnet into your POP3 server and issue the commands yourself,
like:

telnet <pop3server> 110
user <yourname>
pass <yourpassword>
list
uidl
quit

The LIST command will show you the relative index number assigned to a
mail item along with its size. The UIDL command will show you relative
index number along with the long unique identifiers.
 
Thanks. I will check this out. So i need to know the mail item number from
the server?
 
BookerW said:
Thanks. I will check this out. So i need to know the mail item
number from
the server?
Click to expand...


The LIST command will show you the index number for each item (along
with its size). The UIDL command will show the index number for each
item plus its unique identifier number. If the item is no longer on the
mail server, you won't know what was the unique ID that got assigned to
it (and Outlook doesn't provide you with its internal history list of
UIDs, either). You can't use the Message-ID header because that was
generated by the sending mail server (or by the e-mail client), not by
your mail server for it to track your messages.

For those users that are NOW getting duplicated messages but leaving
them on the mail server, you can telnet in and use the LIST command to
show them with their size and then follow with a UIDL command to see
what are their UIDs. Since you are telnetting into the POP3 server, you
don't need to use the client's e-mail program to get those values as
long as you enter the correct login credentials.

My reply wasn't to address why your customers are getting duplicated
e-mails but rather to only address your question on how to get the UIDs
for the messages still sitting in their mailbox. In some cases,
duplicate e-mails is caused by the user configuring far too short a
polling interval in their e-mail client. They set the mail poll
interval to 1 minute, but the first mail poll has not yet completed by
the time the 2nd mail poll gets started, so the messages available for
the first poll are still there (and have not been marked as read by that
e-mail client or a DELE sent in the first mail poll to delete the
message) by the time the second mail poll comes around. See
http://support.microsoft.com/?id=317945 and
http://support.microsoft.com/?id=289942.

E-mail scanning by anti-virus software can also cause the duplication
problem, especially if the AV product doesn't have an option to keep
sending a dummy X header to the e-mail client for its RETR command while
the AV scanner is still interrogating the incoming e-mail. Try
disabling the e-mail scanning feature of your anti-virus software.
 
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