Gmail Address with Canonical Normalization Regex for PHP

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 PHP. 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 PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.

Php Implementation

<?php
// Gmail Address with Canonical Normalization
// ReDoS-checked | RegexVault — Identity & PII > Email Address

define('GMAIL_ADDRESS_WITH_CANONICAL_NORMALIZATION_PATTERN', '/^[a-zA-Z0-9]+(\.[a-zA-Z0-9]+)*(?:\+[^@]*)?@(gmail\.com|googlemail\.com)$/');

function validate_gmail_address_with_canonical_normalization(string $input): bool {
    return (bool) preg_match(GMAIL_ADDRESS_WITH_CANONICAL_NORMALIZATION_PATTERN, $input);
}

// Example
var_dump(validate_gmail_address_with_canonical_normalization("user@gmail.com")); // bool(true)

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Email Address category and has been checked for ReDoS risk. That matters for PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. 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.