README

email-normalizer-php is a PHP port of gmr/email-normalize.

It normalizes email addresses by applying mailbox provider-specific rules such as plus addressing, Gmail dot handling, and Fastmail subdomain aliases. It detects providers from MX records through PHP's native DNS functions, or from a static domain map when DNS lookups are skipped.

This package is for canonicalizing email addresses. It is not an email validator and does not check whether a mailbox exists.

Requirements

• PHP 8.2 or later
• Composer

Installation

composer require sunaoka/email-normalizer-php

Basic Usage

<?php

use function Sunaoka\EmailNormalizer\normalize;

$result = normalize('u.s.e.r+tag@gmail.com');

echo $result->address;           // u.s.e.r+tag@gmail.com
echo $result->normalizedAddress; // user@gmail.com
echo $result->mailboxProvider;   // Google

normalize() creates a temporary Normalizer instance. Reuse Normalizer directly when normalizing many addresses or when cache options matter.

Empty input, including strings that become empty after trimming, throws InvalidArgumentException.

Skipping DNS Lookups

Use skipDns: true when DNS resolution is not desired. In this mode, the package does not call DNS, detects well-known mailbox providers from a static domain map, and returns an empty MX record list.

<?php

use function Sunaoka\EmailNormalizer\normalize;

$result = normalize('user+tag@outlook.com', skipDns: true);

echo $result->normalizedAddress; // user@outlook.com
echo $result->mailboxProvider;   // Microsoft

Reusing a Normalizer

Create a Normalizer instance when normalizing multiple addresses. The MX cache is shared at the package level and respects the configured cache limit and failure caching options.

<?php

use Sunaoka\EmailNormalizer\Normalizer;

$normalizer = new Normalizer(
    cacheLimit: 1024,
    cacheFailures: true,
    failureTtl: 300,
);

$result = $normalizer->normalize('name+tag@example.com');

Constructor options:

• cacheLimit: maximum number of domains kept in the shared MX cache. Default: 1024.
• cacheFailures: cache failed DNS lookups as empty MX records. Default: true.
• failureTtl: seconds to cache failed DNS lookups. Default: 300.
• skipDns: skip DNS and use the static domain map. Default: false.

Result Object

normalize() and Normalizer::normalize() return Sunaoka\EmailNormalizer\Result.

readonly class Result
{
    public string $address;
    public string $normalizedAddress;
    /** @var list<array{priority: int, host: string}> */
    public array $mxRecords;
    public ?string $mailboxProvider;
}

Fields:

• address: original input string.
• normalizedAddress: normalized email address.
• mxRecords: sorted MX records as priority and host pairs.
• mailboxProvider: detected provider name, or null when unknown.

An empty mxRecords list means DNS was skipped or MX lookup failed.

Supported Providers

• Apple
• Fastmail
• Google
• Microsoft
• ProtonMail
• Rackspace
• Yahoo
• Yandex
• Zoho

Normalization Rules

• Plus addressing providers strip the +tag part from the local part.
• Gmail and Googlemail strip periods from the local part.
• Google Workspace custom domains keep periods but strip plus addressing.
• Fastmail can treat the left-most subdomain as the local part.
• Yahoo is detected, but no local-part normalization is applied.

Examples:

normalize('u.s.e.r+tag@gmail.com', skipDns: true)->normalizedAddress;
// user@gmail.com

normalize('user+tag@outlook.com', skipDns: true)->normalizedAddress;
// user@outlook.com

normalize('testing@user.example.com')->normalizedAddress;
// user@example.com when the domain is detected as Fastmail

DNS and Caching

MX records are resolved with dns_get_record($domain, DNS_MX). Records are normalized to lowercase host names and sorted by priority, then host.

The cache is shared by all Normalizer instances. When the cache reaches cacheLimit, the entry with the lowest hit count and oldest access time is removed.

Failed MX lookups return an empty list. When cacheFailures is enabled, failures are cached for failureTtl seconds.

Development

composer install
composer test
composer analyse
composer format

composer analyse runs PHPStan at max level with bleeding edge rules enabled.

License

BSD-3-Clause.

This project is based on the behavior of gmr/email-normalize.