Try using different features of your Email program (such as including attachments) and see if you can make them work properly.
The address you'll be sending this to is not a real address, so the message will bounce (like a rubber cheque!) back to you. This will give you an opportunity to see what a message from a postmaster is like. See if you can understand the message you receive and what it tells you about why the postmaster was unable to deliver the Email.