Will try but suspect won't work.
When I copy in the data file it shows a data structure or data views inconsistent with the data....
There is a file called mailviews.dat and another virtualfolders.dat that I suspect hold the description of what was there ---- the email lists of two accounts and the trash, the lists of auto sort to my dogs mailing list records (emails come to one of the accounts and are auto filtered to this file) the periodic breakup (annually) of the main mail into annual files, the sent files etc that shows up incorrectly.
Am not sure how deleting the msf files will do so, but will try.
Tried it and as suspected the incorrect view of the data files appeared again. As a note there were something like 28 msf files in the parent level of the xxxxxx.default mail database. They did show the names of the file folders I am looking for - mail account1.msf mailaccount2.msf mailaccount12014.msf dogs.msf etc. However when opening thunderbird it showed only one mail account like when I just copy the entire file in and rename with the name of the file autogenerated during install, or the name created by thunderbird profile manager.
What I think needs to happen is something needs to go through the xxxxxx.default directory and find all the msf files or the datafiles associated with the msf files and recreate the datastructure of what was there and then recreate the dataviews when thunderbird starts -- what I am just guessing is contained in the mailviews.dat file or the virtualfolders.dat file.
Have deleted the oldbackup and am copying another backup into that location.
Any further ideas?