If you are attempting to recover data from BlackBerry backups (.bbb), you best choice would be to use utilities like the ABC BlackBerry Converter that can recover plenty of various data from BB backups, such as .doc documents exported from emails.
Convert BlackBerry backup (post 2012) to Document file.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert bbb to doc on Windows
A conversion utility for BlackBerry backups
Convert from bbb file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.