Welcome @andersgs,
I may be misinterpreting your post, but are you trying to write code to validate user input in form to ensure it is a valid email format?
If so, could you use the built in functionality Anvil has to change the ‘type’ of your TextBox to ‘email’. This is found in the Properties under Place Holder. See image below.
You could then use the Validator as described in the Form Validation Article
