In the app I aluded to above, the filenames were EmployeeID_SomeSuffix_SomeDate.extension Most of the files were .jpg but we had .docx, .xlxs,, .pdf, and possibly others also. The important part was the first n caracters to the left of the first underscore were the EmployeeID. Looking up the EmployeeID gave me the way to obtain the folder path names.
The files were handled by a third party service bureau, they received printed documents and scanned them or emails with attachments. They uploaded them to our FTP site an the Access app down loaded them a couple of times a day into a common folder. As part of the import process, it logged the file name and moved the file to the correct folder. If there was an error because a file was named incorrectly, the file was moved to an error folder where a human had to figure out the problem and rename the file. Then when all the files in the bulk mail folder had been processed and moved, the originals were deleted leaving the folder empty for the next download.