To request a reply for one item, open an item view, click the Send Options tab, then click General.
or
To request a reply for all items you send, click Tools, click Options, then click Send.
Click Reply Requested, then specify when you want to receive the reply.
The recipient sees next to the message. If you select When Convenient, "Reply Requested: When convenient" appears at the top of the message. If you select Within x Days, "Reply Requested: By xx/xx/xx" appears at the top of the message.
Click Send.