Automatically declines to send read receipts in Google Mail
Has your Google Apps administrator enabled read receipts for your domain? Are you fed up of clicking 'Not now' every time Google Mail asks you whether it should send a read receipt? Do you wish there was a global 'don't send read receipts' setting?
If so, this extension is for you! When you install it, it will automatically choose 'Not now' every time you're asked whether to send a read receipt, and it's so fast you won't even see the dialog.
If you don't trust me, and want to see the source, it's at
N.B. this extension is only useful for Google Apps users who have read receipts enabled - it's not for 'consumer' GMail accounts.