To ask for a read-receipt, please press the vertical 3-dots menu in the compose screen and choose Enable Read Receipt.

You can also set this option as default by tapping More (o o o)| Various Account Settings | tap the account | Advanced Account Settings | Enable Read Receipt.

Please note that only recipients using email servers that support this capability on the other side, such as Exchange servers, will report back read-receipt messages to TypeApp.

Also, on some clients, the recipient has to approve before the read-receipt will be sent and acknowledge acceptance.