I’m working on a project that involves sending messages to a Microsoft Teams channel using the Microsoft Graph API. I have a specific requirement where:
If a user’s email exists in the teams channel, the message should be sent as a reply from that user.
If the user’s email doesn’t exist in the channel, the message should be sent from a bot or a service account.

I’m using user’s token for authentication. Is there any way to achieve this conditional sending of messages using the Microsoft Graph API?

Here is a rough outline of what I’m trying to accomplish:
Check if the email exists in the teams channel.
If it does, send the message as the user.
If it doesn’t, send the message as a bot or service account.

Any guidance or examples on how to implement this would be greatly appreciated. Thank you!