Is there any way of using email-to-forum to receive emails from unknown addresses?

I am trying to collect notification emails from online services (Bitbucket in this first case) under a forum post, but it seems that only users with access to the project can send email to Zoho. 

I don't want to add the online services' email addresses to the project because then I have no way to prevent that account from accessing the whole project's data.

Thanks for any suggestions!