#!/bin/cat
$Id: FAQ.POP3.txt,v 1.3 2018/05/24 11:34:30 gilles Exp gilles $

This document is also available online at
https://imapsync.lamiral.info/FAQ.d/
https://imapsync.lamiral.info/FAQ.d/FAQ.POP3.txt


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               Imapsync tips about POP3.
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Questions answered here are:

Q. Can I use imapsync to migrate emails from pop3 server to imap server?

Q. How can I handle those terrible POP-leaving-a-copy users?
   POP-leaving-a-copy clients will download a new copy of all 
   their emails after a migration, which is a big pain and 
   causes hundreds of support calls. 

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Q. Can I use imapsync to migrate emails from pop3 server to imap server?

R1. No, but you can migrate emails from a pop3 server to an imap server 
with the command line tool pop2imap:
http://www.linux-france.org/prj/pop2imap/

R2. Yes, sometimes, because many pop3 servers runs in parallel
with an imap server on exactly the same mailboxes. They serve 
the same INBOX (imap serves INBOX and several other folders, 
pop3 serves only INBOX).
So have a try with imapsync on the same host1.

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Q. How can I handle those terrible POP-leaving-a-copy users?
   POP-leaving-a-copy clients will download a new copy of all 
   their emails after a migration, which is a big pain and 
   causes hundreds of support calls. 


R. A discussion about this issue
http://www.linux-france.org/prj/imapsync_list/msg02622.html
http://www.linux-france.org/prj/imapsync_list/msg02623.html
My reply was not very good
http://www.linux-france.org/prj/imapsync_list/msg02624.html
It's because I wrote pop2imap and it uses a stateless
mechanism to avoid duplicates, I wasn't aware of UIDL.

Here is a better response to handle and fix this problem, I hope:
If the pop mailboxes are known and known to be regularly fetched, then
all the INBOX messages, or at least the "old" ones, can be moved in an
subfolder INBOX_back. It requires to have "access" to the POP
sessions. The POP server log file is usually enough to know which
account opened a pop connection, and when.

See also Rick Sanders discussion about this issue:
https://www.emailquestions.com/threads/how-to-prevent-duplicate-emails-after-server-migration-for-pop3-users-with-leave-mail-on-server.8109/


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