Verify the name and address of the check recipient. Then, fill out the check with the information spelled clearly and correctly. On the back of the check, where it's to be endorsed by the recipient, write "For deposit only." This means the recipient must deposit the check into an account.
Enclose the check in another piece of paper so that it cannot be seen. You can also purchase a security envelope, which are designed to mask contents.
Take the check, sealed in its envelope, to the post office. You incur less risk by handing it to a postal employee rather than putting the check in your mailbox. Double-check the postage cost for sending the check.
Send the check by certified or express mail. Certified mail means that someone must sign for the check when it is received, and the receipt is mailed back to you with that signature as proof that your intended party signed for and received the check.