Email Address Validity Checker using Python

Generally, to check the email address is valid, we have to look for '@' sign. Because every email address has @ sign. But specifically, we can check if the email is valid by looking at four parts which are name, @ sign, domain name, and top-level domain name.

For example. valid email address: johnDoe.123@gmail.com

johnDoe.123 -- name ( can include upper case/lower case letters, digits and some special characters )
followed by @ sign
gmail -- domain name ( can include upper case/lower case letters, hyphen and period)
.com -- top level domain ( can include at least two upper or lower case letters)

#ref: John Pollard, What are the rules for email address syntax? – Validity Help Center (returnpath.com)

So as for python program to check a valid email address, use python regular expression (https://github.com/python/cpython/tree/3.9/Lib/re.py) to make a pattern of valid email address. If the email matches with the pattern, then it will judge as a valid email address, if not it will judge as an invalid email address.

First we need to import re library.

import re

Then, create a regex pattern

pattern=r'[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}'

Check if the email matches with the pattern. If yes, print out as "Valid", otherwise print out as "Invalid"

if re.search(pattern,email):
print("Valid Email")
else:
print("Invalid Email")

The complete code snippet is as follow.

# Email Verifier...
import re
def emailVerifier(email):
pattern=r'[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}'
if re.search(pattern,email):
print("Valid Email")
else:
print("Invalid Email")

To run this python function, just simply call the function name with one parameter which will be the email address you want to check.