The email notifications generated by instant messages don't have reply-to field set, even if recipient is allowed to see the email address of the sender.

Steps to reproduce

1. Check if User 2 may see the email address of User 1
2. Send an instant message from User 1 to User 2
3. Look at the email notification

Expected result:

The email notification has reply-to attribute set to User 1's email

Current result:

Reply-to is set to the system's no-reply address.