I am facing an old-fashioned setup, where emails are fetched (and deleted) using POP3 from several accounts, and stored in Thunderbird's "local folders", organized in folders and subfolders.
The project is to move all that mess into a single Gmail account, so that everything can be accessed at a single, remote location using IMAP.
Would the migration be as easy as just, in Thunderbird, copying the emails from the local folders to the remote IMAP account, or are there caveats to consider? Would some information be lost/altered in the process?
Best Answer
In Thunderbird, add the Gmail account as IMAP (not POP3, which might be the default option).
Verify the account sync is working.
Create each folder manually, as mentioned above. The folder tree structure is difficult to copy.
Copy items from each folder - blocks of up to 5000 messages worked fine for me