normalize-gmail-address

Validate and normalize a Gmail Address

Why

If you don't normalize Gmail addresses, one Google Account can be used to have practically infinite email addresses. Because if you own example@gmail.com, you can receive Emails at example+zczgmrebqgrjvgk@gmail.com or at any other string after the plus sign.

Usage

1. Respect your users preferences by sending Emails to the Email address they provided
2. But check for account duplicates with the normalized Gmail address

import EmailAddresses from 'email-addresses'
import normalizeGmailAddress from 'normalize-gmail-address'

function userSignup(emailAddress, hashedPassword) {
  // Check if Email is valid
  const parsed = EmailAddresses.parseOneAddress(emailAddress)
  if (!parsed || parsed.type !== 'mailbox') throw new Error('Invalid Email address')

  // Distinguish because Emails addresses may be case sensitive
  // or in case of gmail, users may want Emails to end up at the provided alias
  const emailAddressForSendingEmails = parsed.address
  let emailAddressForCheckingAccountExists = parsed.address.toLowerCase()

  try {
    emailAddressForCheckingAccountExists = normalizeGmailAddress(parsed.address)
  } catch (error) {
    if (error.code !== 'NOT_GMAIL') throw new Error('Invalid Gmail address')
  }

  if (yourDatabase.doesAccountExist(emailAddressForCheckingAccountExists)) throw new Error('Account already exists')

  // ...
}

Format of a Email/Gmail address

ilikemath+1+1=2@gmail.com

• ilikemath+1+1=2 is called the local part
• gmail.com is called the domain
• ilikemath is called the username (only for gmail.com and googlemail.com)
• 1+1=2 is called the alias (only for gmail.com and googlemail.com)