I am trying to create an add-in to implement tracking an email using lead-boxer(https://leadboxer.com/) where I can get all the details of the user who has opened my email. I had implemented the add-in to send an email with an image tag with the link. So I am getting the details of users.
Now I want to add a read receipt kind of action item button on the sent email and I am not getting any solution, I want to show that icon with sent email action items which is shown here(https://i.ibb.co/nwQRMzC/Capture.png).
I had tried creating another add-in but I could not find any way to place that button on the required place i.e. with email action items.
Also, I want to make a call to API when email sender opens the sent email to check if the recipient has opened that email or not.
Outlook doesn't provide anything for customizing the reading pane action buttons. However, you may create your own form instead if you develop a COM add-in. So, you need to develop a COM add-in to be able to customize the Outlook as much as you want. See Walkthrough: Create your first VSTO Add-in for Outlook to get started quickly. Web add-ins provide a limited capability for UI customization.
