There is a way to add an email to Todoist by sending it to a special address, the only thing that annoing me, that it doesn’t keep a link to the message in Mail.app.

I created a simple Alfred workflow, which takes the selected messages in Mail.app, creates a Markdown links as [email subject](message://message_id) and send it to Todoist Inbox using its API.

You can find the details about installation and usage in sneawo/mailapp-to-todoist repository.