why isn't an email address a string code example

Example 1: regex pattern to validate email

[a-zA-Z0-9._-]{3,}@[a-zA-Z0-9.-]{3,}\.[a-zA-Z]{2,4}

Example 2: regex to validate email

# Python
r"(^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$)"