Actually the enclosure is in the mail, though in a different layer. By
clicking the turned edge at the bottom left corner of the standard
mailer, you can find enclosures in the original addresses mailer.
Also, a popup menu (triangle) appears to the right of the "From" field.
This popup menu lists names of all forwarding individuals. A paper
clip may appear beside some names in the popup menu indicating an
enclosure. Selecting names from the popup menu allows instant access
to the standard mailer page addresses.