AutoOpen Outlook web add-in task pane functionally

We are using OnMessageSend LaunchEvent and we are trying to open web add-in when OnMessageSend Event fired but we are not able to open outlook add-in task pane functionally.

AutoOpen feature is still not available in outlook web add-in.

Please also check raised git ticket as below-

https://github.com/OfficeDev/office-js/issues/3445

Please consider this feature when you go through the planning process.

Thanks.