After I updated to Thunderbird 24.4, recent: mode in Gmail account fails with "Sending of password did not succeed. Mail server pop.gmail.com responded: Username and password not accepted. If I remove "recent:" from username, it works. No changes where made to account setting for the last couple of years, the only thing that changed is upgrade to 24.4. I also created a new account profile in Outlook with "recent" and it is working. This makes me think that in 24.4 update something is broken with the recent: mode. The gmail "recent:" mode enables more than one device to get the same messages. You use "recent:name@gmail.com" instead of "name@gmail.com" in the username field in acoount settings. This way you get the last 30 days email regardless of which device grabs them first, on all devices.