I know you can specify a list of source folders for vfolders to match against, but I'd also like the ability to specify a rule like "Location contains ...."  (where 'location' corresponds to the 'Location' column in the mail view*).

Use case: I'm required by my company to have an ARCHIVE folder in my IMAP account, that contains all the mails older than 300 days that I want to keep (otherwise they get automatically deleted after a while).  So, I have a vfolder set up that lists all my mails older than 300 days, which I go through now and again deciding which emails I want to keep.

Of course, that vfolder also contains everything in the ARCHIVE folder, unless I go through and manually add dozens and dozens of folders to the 'sources' list.  That's tedious in the extreme, and I need to remember to update the vfolder rules every time I add a new subfolder to the ARCHIVE.

With a location matching rule, this would be trivial:

Date received is before 300 days ago
Location does not contain 'ARCHIVE'

(*Why _is_ this column called 'location', and not something more recognisable like 'folder' or 'mailbox'?  It's particularly confusing when the app also deals with calendar appointments, which also have 'locations'...)