Sometimes its annoying when a person has return receipts enabled whenever they send out an email.
Thunderbird users will see a message box confirming "The sender of this message has asked to be notified when you read this message. Do you wish to notify the sender?" every time you read a new email from them.
- Go to the "Tools" menu and select "Options".
- Select the "Advanced" tab and then "General"
- Click on the "Return Receipts" button.
- Select "Never send a return receipt".
- Crack open some celebration drinks!