[newbie] Backing up emails under Thunderbird

[Peter Mann]

Chasing location for where the inbox and sent emails are stored, so I can back up prior to installing a later version of Linux.  Looking in file:/home/peter/.thunderbird/fw7h4hlb.default/Mail/Local Folders/Inbox.sbd one finds the cupboard is bare. Can someone help with where Thunderbird may have hidden away those elusive files ?