[Feature Request] Compose - Delivery Status Notification & Attach My Public Key

On Mozilla Thunderbird when Composing a new email, there's a few options including Return Receipt, Delivery Status Notification, Do Not Encrypt or Require Encryption, Digitally Sign This Message and Attach My Public Key 🗝.

The two that K-9 Mail does not have which would be useful are Delivery Status Notification and Attach My Public Key.

It would be great if you could add those two to the top right menu on the Compose view. Although I imagine that you might have to work with the Developer(s) for OpenKeyChain to add the Attach My Public Key option.

Also could you please make it clearer when either of those are selected, such as make a checkmark ✅ appear when selected? Because right now when we tap on "Return Receipt" for example, there's just a toast notification that appears at the bottom for a brief moment.

Thank you.

Start from the Compose view's top-right menu and inspect how the existing Return Receipt option is represented and selected. Determine the integration point for Delivery Status Notification and Attach My Public Key, including coordination with OpenKeyChain, and consider the request complete when both options are available with persistent checkmarks showing their selection.