iMessage - How to turn off read receipts
Here's how to prevent the Messages app of Mac OS X Yosemite from sending read receipts. The procedure is as follows:
- Open the Messages app.
- Click on the Messages menu > Preferences.
- Go to the Accounts tab.
- Select an account (if multiple).
- Uncheck "Send read receipts - Allow others to be notified when you have read their messages".