Swift Email Validator

A lightweight Swift library for validating, normalizing, and inspecting email addresses. Built on WordPress-inspired, RFC 5321/5322-aware validation logic, it exposes a clean set of String, Array, and Collection extensions so you can check, filter, and analyze emails with natural, expressive syntax.

Features

• 🎯 RFC-aware validation — Enforces length limits, local/domain rules, subdomain checks, and TLD constraints for accurate results.
• ✅ Simple boolean checks — "user@example.com".isEmail returns a plain Bool with no setup required.
• 🌍 Internationalized addresses — Opt in with isInternationalizedEmail to accept Unicode (EAI / IDN) local parts and domains, while the default stays ASCII-only.
• 🔤 Email normalization — Lowercases the domain while preserving the local part's original case per RFC standards.
• ✂️ Component extraction — Pull out the local part and domain from any valid address.
• 🏷️ Provider detection — Identify 90+ consumer providers (Gmail, Outlook, Yahoo, iCloud, ProtonMail, and more) from the domain.
• 👤 Personal vs. business — Distinguish recognized personal email providers from custom/business domains.
• 📚 Array filtering — validEmails, normalizedEmails, and their …IfAny optional variants for batch handling.
• 🔢 Collection counting — validEmailCount and hasValidEmails for quick aggregate checks.
• 🧱 Zero dependencies — Pure Foundation, no third-party packages.
• ⚡ Lightweight & fast — Lazy filtering and minimal allocations for large collections.

Requirements

• iOS 13.0+ / macOS 10.15+ / tvOS 13.0+ / watchOS 6.0+
• Swift 6.1+
• Xcode 16.0+

Installation

Swift Package Manager

dependencies: [
    .package(url: "https://github.com/arraypress/swift-email-validator.git", from: "1.0.0")
]

Usage

Validating a single email

import EmailValidator

if "user@example.com".isEmail {
    print("Valid email!")
}

"invalid".isEmail        // false
"a@b.co".isEmail         // true

Validating internationalized (EAI / IDN) emails

By default validation is ASCII-only (WordPress parity). To accept internationalized addresses — Unicode local parts per RFC 6531 (SMTPUTF8) and internationalized domain names per RFC 5890 — use isInternationalizedEmail:

import EmailValidator

"test@münchen.de".isInternationalizedEmail    // true
"tëst@example.com".isInternationalizedEmail   // true
"почта@почта.рф".isInternationalizedEmail     // true

"test@münchen.de".isEmail                     // false (default is ASCII-only)

Control characters, whitespace, and structural characters (<, >, (, ), …) are still rejected. This is validation-only: addresses are checked as the Unicode U-labels you type, without Punycode/A-label conversion, so length limits are enforced in characters rather than encoded octets.

Normalizing and extracting components

import EmailValidator

let normalized = "User@EXAMPLE.COM".normalizedEmail
// "User@example.com" (domain lowercased, local part preserved)

"user.name@example.com".emailLocalPart   // "user.name"
"user@sub.example.com".emailDomain       // "sub.example.com"

Detecting providers

import EmailValidator

"user@gmail.com".emailProvider           // "Gmail"
"user@outlook.com".emailProvider         // "Outlook"
"user@company.com".emailProvider         // nil

"user@gmail.com".isPersonalEmailProvider     // true
"support@startup.io".isPersonalEmailProvider // false

Working with arrays and collections

import EmailValidator

let emails = ["User@EXAMPLE.COM", "invalid", "test@DOMAIN.ORG"]

emails.validEmails        // ["User@EXAMPLE.COM", "test@DOMAIN.ORG"]
emails.normalizedEmails   // ["User@example.com", "test@domain.org"]
emails.validEmailCount    // 2
emails.hasValidEmails     // true

// Optional variants return nil instead of an empty array
if let valid = emails.validEmailsIfAny {
    print("Found \(valid.count) valid emails")
}

if let normalized = emails.normalizedEmailsIfAny {
    print(normalized)
}

How It Works

Validation trims whitespace, then enforces RFC 5321/5322 constraints:

• Length — between 6 and 254 characters overall; local part ≤ 64; domain ≤ 253.
• Structure — exactly one @, not in the first position, with non-empty local and domain parts.
• Local part — ASCII only, valid atext characters plus periods, no leading/trailing or consecutive dots.
• Domain — at least two labels, no consecutive dots, each subdomain ≤ 63 characters and alphanumeric/hyphen, and a TLD of ASCII letters at least 2 characters long.

When using isInternationalizedEmail, the same structural rules apply but Unicode letters and numbers are additionally permitted in the local part and domain labels (and Unicode-letter TLDs such as .рф are accepted).

Testing

swift test

The test suite covers validation edge cases, normalization, component extraction, provider detection, and the array/collection helpers.

License

MIT License — see LICENSE file for details.

Author

Created by David Sherlock (ArrayPress) in 2026.