[Evolution] "Scanning folders" and folder behavior

[Tom Jennings <tomj wps com>]

I'm wondering if there's a way to selectively control which folders are
scanned for new email, and which are not, rather than an all-off or
all-on mode.

I keep all of my sent and deleted email (back to 1994, with holes)
available to my MUA (Evolution at the moment). I keep them in nested
directories:

        1997
                Jan
                        spool file with messages
                Feb
                        spool file with messages

etc. 

Obviously, the contents of these folders doesn't need to be scanned for
new mail. The folders containing active lists (evolution, etc) do.

Can I do this? There's this "subscribe to folder" phrase bandied about
temptingly in menus and such but I find no menu, comman, documentationor
web page about it as a concept.