Hello, Thank you for your support, Can I migrate the mail in Thunderbird Pop3 to IMAP but without losing the folder filters and emails from pop3. I have already changed pop.gmail.com (port 995) by imap.gmail.com (port993) but it does not work. Thank you, Ilyas.

To change from POP to IMAP, it's not sufficient to just change the server settings - the account has to be added independently as an IMAP account.

http://kb.mozillazine.org/Convert_a_POP_account_to_a_IMAP_account

Filters can be transferred between accounts by copying the msgFilterRules.dat file in the account subfolder of Mail in the profile to the account subfolder of ImapMail.

Copying mail from a POP account stored locally to an IMAP folder is a bit more complex, and best done in small batches of messages at a time.

Hello Sir,

Thank you for your support and for your message, For the email capacity it is more than 70GB and for the the folder filters is more 20 filters. So it has no impact on losing emails sir.

Best Regards, Ilyas.