Forgotten Attachment Detector

(This is a feature on Gmail Labs, which you’ll find under the settings label in Gmail)

The use case is so simple. The user writes “Attached you’ll find” or “in the attached” or something like that – basically anywhere they use the word “attached” – if there is no attachment, ask the user if that’s ok.

The number of times you say “attached” and don’t mean to attach a file is presumably outweighed by the number of times you mean to attach a file but hit send before you attach it.

How can I get this in Apple Mail or (sigh of the reluctant user) Entourage to do this?