missing stamp?

Postman Postman don't delay
Send this letter on its way.

(1)
like an oversized
piece of mail
I refuse to fit
through a slot
that others
slip through


(2)
we are letters
sent from here
going there

some Standard
others Special Delivery

(3)
others sent
with good intention
wind up
at a Dead Letter Office
never reaching
their destination

all SWAK