One of the reasons I stuck with POP, rather than switching to IMAP earlier, was that I maintain several quite large archive mail folders and I didn’t want these synchronized to the relatively small amount of memory in my smartphone. However, IMAP is quite happy to ignore Thunderbird’s “Local Folders” so, simply placing the archives in this area, avoids any potential storage limitations.
In my case it was simply necessary to move my existing archive folders to an “Archives” sub-folder under “Local Folders” on my main computer before I created an IMAP account. Any mail messages subsequently dragged and dropped into one of the archives is then effectively moved out of IMAP’s synchronization process. Clearly, as a result of doing this, such messages are no longer available on other synchronized devices but, since I don’t have any need for frequent access to these files, this isn’t a problem for me.
However, the interesting feature of using Thunderbird to access IMAP folders on my ISP’s mail server is how the Trash folder is handled.
The main mail folder is named Inbox. It seems that the IMAP server insists on having a sub-folder located at Inbox – INBOX – Trash. INBOX is displayed in all-caps and italics, and a light-grey font is used, almost as though it is some sort of hidden folder. Trash appears as a sub-folder, but is displayed in a normal font.
However, this isn’t the end of the story. Thunderbird also insists on having a Trash folder. So, in addition to the above-noted Inbox – INBOX – Trash, I also have an Inbox – Trash folder. (Confused yet?!)
The net result is that I see two “Trash” folders in my main set of mail folders. There is “Inbox – INBOX – Trash” and “ Inbox – Trash”.
Now, while this is “interesting”, it is also quite irrelevant for my usage of Thunderbird. By default, Thunderbird uses the Trash folder (i.e. Inbox – Trash). But, also by default, Thunderbird is set to “Empty Trash on Exit” (Edit – Account Settings – Server Settings – Message Storage). Consequently, since I leave this default setting in place, I don’t really care where trash is stored since the Trash folder is effectively always empty!
Converting Thunderbird from POP to IMAP
IMAP Trash folder