Cool [Q] Change POP3 to IMAP

Hi,

iŽam using the Stock E-Mail App.
Is it possible to change a working POP3 Account into IMAP without loosing all Mails?

With Titanium Backup i can save all Mails, but after the recovery (only Data) into an IMAP Account the IMAP Account was changed into a POP3!

Please help.
Thanks.

Another Way is to save the Mail localy, but i canŽt import it into the new Mail-Account (Stock App)