To whom it may concern, I'm trying to change access to my Gmail account from POP to IMAP per instructions at http://kb.mozillazine.org/Convert_a_POP_account_to_a_IMAP_account AND NOT SUCCEEDING. In the past, although I used only POP3 mail, the Gmail server settings showed both POP and IMAP enabled. I don't understand why, but it worked for years. However in recent weeks POP download has become increasingly intermittent (usually zero) and despite a couple weeks' assistance from both the Thunderbird and Gmail user groups, no solution could be found. Since it would be convenient to be able to access mail via multiple devices, I'm willing to convert to IMAP to escape from this download problem, and store mail locally if needed on this Win 10 laptop as I did with POP. As part of this effort I have disabled POP at the server, although Thunderbird still shows a POP download account. But... I am hung up at the step that says: Create the IMAP account using Tools -> Account Settings -> Account Actions -> Add Account When I attempt to do this, two things happen: (1) A Google page appears, requesting that I log in to my Google account. But it doesn't accept my Gmail address. (2) Meanwhile the Thunderbird Account Setup page displays a notice: "Unable to log in at server. Probably wrong configuration, username or password." This makes no sense to me. POP is now disabled at the server, and IMAP is enabled. At some point during multiple loops through this process I managed to delete my Thunderbird POP3 server account, with the result that all my several hundred email folders disappeared. Fortunately I had backed up the Thunderbird profile prior to starting on what I mistakenly thought would be a reasonably straightforward process. That allowed me to restore my email to the Local Folders; it took a few hours but worked. From reading your articles it appears this makes them safe from server changes. I have subsequently restored my Thunderbird POP3 incoming mail setting, but it really doesn't matter because the Gmail server won't download my mail. It seems that the next challenge is finding a way to convert the Server setting in Thunderbird from POP to IMAP. I can't get past this issue where Google appears not to recognize my Gmail address, thus the IMAP server linkage can't be created. I am basically 100% certain that there is no problem with my Google/Gmail account. So I could definitely use some assistance. After several weeks now, having to read my email on the Gmail website is getting really old. Martt Harding