Good guide on how to use discourse via email

Yes, creating topics via email is only possible if the site has been configured for it. It’s a great approach for customer support forums. It’s how we have customers contact our support team at Discourse.

On any sites that I’m aware of that allow topics to be created by email, the site shares the email address that is used to create the topics. Details about how to set it up are here: Start a New Topic via Email ✉.