"Is there any way to selectively enable/disable the read receipts option?"

You can control it either by recipient or by keywords in the subject or message body. All you need to do is create a "Check messages after sending" rule.

1. Open the Rules wizard Select the option to create a blank rule
2. Choose 'Check messages after sending' from the rules dialog.
3. Select the conditions you want to check for and enter the criteria.
4. Choose 'notify me when it is read' as the action.
5. Enter exceptions, if needed, and save the rule.

Now every message you send that meets the conditions you chose will include a read receipt request.