Some users, particularly connector users, want an Outlook-like
auto-archive command, that moves old data out of active folders into
a local archive.

Outlook's AutoArchive is very complicated. There are a zillion options,
some of which contradict other options.

The important bits are: you need to be able to turn it on and off,
say how often you want autoarchiving to run (actually, I don't
see any reason we couldn't always run it at startup), and say where
things should be archived to. (In Outlook, you pick a PST file, and
it mirrors your Exchange folder hierarchy into it.)

Then for each folder, you can configure whether or not it participates
in AutoArchiving, and if so, how old things have to be before they get
archived. You can also say that things should just be nuked rather
than being archived in some folders. And contact folders can not be
autoarchived.

Outlook also has a plain "Archive" command, which you can use to
manually archive everything older than a certain point.