How do I invite users to an app with a dedicated URL in


Unfortunately there isn't a way to send an email with the dedicated URL with Custom domains aren't designed to provide a complete white label offering for customers. At the end of the day, users that you invite are members of first and foremost, and the account holder has the ability to constrain which applications these users have access to. 

We'd suggest in this case adding users to the application without sending an email, then composing your own invitation email outside of and include your dedicated URL there.