A method and computer program product includes, at a sender, identifying a forward item including a transmit portion and a retain portion, generating a tag, associating the tag with the retain portion, sending the transmit portion, but not the tag, to a target; at the target, receiving the transmit portion, identifying a return portion corresponding to the transmit portion, independently generating the tag, associating the tag with the return portion, sending the return portion and the tag to the sender; and at the sender, receiving the return portion and the tag, identifying the retain portion using the tag, and associating the return portion with the retain portion to create a reverse item.