Is email function is not working in all devices

Hello everyone,

I built and deployed a platform last week, which includes authentication. When you press “Sign In” or “Sign Up,” it verifies the email with an if condition that includes the is_email function.

The issue is that it’s working on my phone and PC, but when I deployed it, it didn’t work for some people.

Can you please help me identify the problem, and are there any alternatives I can consider?

urgent please
thank you