Hi @Brian16 and welcome to the Forum!
As it stands, it is no possible to create a Task by email if you are not a member or guest of the Project.
Li @Cary mentioned, one workaround could be creating an email account set up to create Tasks in that particular Project every time this account receives an email. It is called Auto-Forward Emails and you can learn how to do it in the following article: Turning emails into Asana tasks | Product guide • Asana Product Guide
I hope this helps! Let me know if you have any follow-up questions! Have a great Friday!