Email with Plus Addressing Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching email with plus addressing, ported and verified for JavaScript. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your JavaScript project — whether you're validating in an Express middleware, a Next.js API route, or a client-side form.

Javascript Implementation

// Email with Plus Addressing
// ReDoS-safe | RegexVault — Web & Network > Misc

const emailWithPlusAddressingRegex = /^([a-zA-Z0-9.!#$%&'*\/=?^_`{|}~\-]{1,64})\+([a-zA-Z0-9.\-_]{1,64})@([a-zA-Z0-9](?:[a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?)*)$/i;

function validateEmailWithPlusAddressing(input: string): boolean {
  return emailWithPlusAddressingRegex.test(input);
}

// Example
console.log(validateEmailWithPlusAddressing("user+tag@example.com")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > Misc category and carries a ReDoS-safe certification. That matters for JavaScript developers because especially critical in long-running Node.js event loops where a ReDoS vulnerability can block the entire process. 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

Capture group 1: local base, group 2: plus tag, group 3: domain. Use to detect sub-addressing and optionally strip the tag before lookup. Gmail, Outlook, and Fastmail support plus addressing.