After installing a new system (Ubuntu 10.04.1 Desktop), I copied the
/var/mail dir content to the new system and install - same config - dovecot as an Imap(s) server.
To test the new setup, first the .thunderbird / .mozilla-thunderbird where copied to the new system / same user name (same uid) and Thunderbird was installed.
After a while, Thunderbird downloaded twice the number of emails (300 -> 600), built again its index, then started to download another 600 (double) emails, making it x 4.
My iphone using the same Imap server got also new messages notifications for the duplicates.
So, I wonder if the problem would come
- from Thunderbird while rebuilding its indexes (creating new mails replicated dovecot side)
- from dovecot, with the mix of old / new data.
My first guess would be Thunderbird, but I cannot be sure, and don't want to let the mails being doubled continuously (well, after the night the FS would be full...).
"hoping" someone got a similar problem to be shared... thank you.