Gmail Address with Canonical Normalization Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching gmail address with canonical normalization, ported and verified for Python. Identity and credential patterns need both correctness and safety, since they're frequent targets for adversarial input. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# Gmail Address with Canonical Normalization
# ReDoS-safe | RegexVault — Identity & PII > Email Address

import re

gmail_address_with_canonical_normalization_pattern = re.compile(r'^[a-zA-Z0-9]+(\.[a-zA-Z0-9]+)*(?:\+[^@]*)?@(gmail\.com|googlemail\.com)$')

def validate_gmail_address_with_canonical_normalization(value: str) -> bool:
    return bool(gmail_address_with_canonical_normalization_pattern.fullmatch(value))

# Example
print(validate_gmail_address_with_canonical_normalization("user@gmail.com"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Email Address category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Gmail canonicalization: strip dots from local part, strip everything from + to @ inclusive, lowercase. u.s.e.r+tag@gmail.com and user@gmail.com deliver to the same inbox. Also, googlemail.com is an alias for gmail.com.