I once worked with a guy who had an Outlook rule that immediately marked new mail as read ( and flagged 'to action' or something like that ) specifically to defeat Exchange recall.

Admittedly he did manage to harvest some interesting information but mainly it was just managers trying to correct typos.

It was effective before blackberries (and the iphones that killed them). Basically it worked when there was a chance that you'd hit recall before anyone's mail client would have actually pulled it down.

I saw people (try to) use it a decade ago. Same result.

Well, if it succeeded, you wouldn't see it.