This is a choice under the Options menu in a Write window.

Unfortunately, I am inquiring about a "read" receipt. In Outlook Express I can request a "read" receipt from the recipient. It is not the same as a delivery receipt. When the recipient opens his email he gets a popup asking if he wants to acknowledge the "read" receipt back to the sender. If he selects "YES" the sender is mailed a message that the recipient is "reading" the email. I want my employees to acknowledge that they are "reading" the email after I send it. A delivery receipt does not give me verification that the message is being read. There seems to be a bit of confusion about a "delivery receipt" and a "read receipt". Neither of the choices under OPTIONS gives you back a "read" receipt. I am hoping that there might be an add-on that provides the same service as offered by Outlook Express. I tested the two entries under "OPTIONS" and was indeed sent a message that the email had been delivered. I did not receive a verification that the receiver had opened the email. Thanks

There is no confusion here. If you add a Return Receipt the recipient will get a request to acknowledge your message.

There is no way to confirm that the recipient has READ the message. That is not physically possible. Even with Return Receipt it is totally optional to acknowledge the message. Personally I never do.

Thunderbird's explanation. The one that counts since this is not Outlook Express or any other Microsoft product.

http://kb.mozillazine.org/Figuring_out_whether_the_recipient_read_your_message