creating fillable pdf with email link

You are in effect trying to re-invent the wheel with something that will never be as reliable as the tools that exist for this purpose. Using a submit button in a PDF is nothing short of a crapshoot.

Since this is obviously intended to be used on the web, I encourage you to create a proper web-based form or even use a free google form for this purpose.

Assuming you are seeking help with that email submission button, the full functionality you seek is available in Acrobat Pro: 

https://knowit.ok.ubc.ca/article/how-do-i-add-email-submission-to-a-pdf-form-393.html#:~:text=On%20the%20top%20right%20of,not%20the%20actual%20button%20label.