I finally gave up on this, and will be giving up Thunderbird just as soon as I can find a suitable alternative. In the meantime, I've had to just get used to using delete for messages I know I'll never have a need for in the future, and A for archiving/preserving all others (in the All Mail "folder" or any other you designate).
I finally gave up on this, and will be giving up Thunderbird just as soon as I can find a suitable alternative. In the meantime, I've had to just get used to using delete for messages I know I'll never have a need for in the future, and A for archiving/ preserving all others (in the All Mail "folder" or any other you designate).