@synotech/utils/src/verymail.ts

a collection of utilities for internal use

import tlds from './assets/tlds';
import { Resolver } from 'node:dns';
const resolver = new Resolver();
resolver.setServers(['8.8.8.8']);

const dnsResolver = (domain: string): Promise<boolean> => {
	return new Promise((resolve) => {
		resolver.resolveMx(domain, (err, addresses) => {
			try {
				if (err || !addresses || addresses.length === 0) {
					console.trace(err);
					resolve(false);
				} else {
					addresses.sort((a, b) => a.priority - b.priority);
					const priorityRecord = addresses[0];
					if (!priorityRecord.exchange) resolve(false);
					resolver.resolve(priorityRecord.exchange, (err) => {
						if (err) {
							console.trace(err);
							resolve(false);
						} else {
							resolve(true);
						}
					});
				}
			} catch (error) {
				console.trace(error);
				resolve(false);
			}
		});
	});
};

/**
 * This method validates email address
 * @param {Object} contact
 * @param {String} contact.email the email to be validated
 * @return {boolean}  {Promise<boolean>} a boolean value indicating if the email is valid or not
 * @memberof Verymail
 * @example
 *  const isValid = await validateEmail({
 *      email: 'user@example.com',
 *  })
 */
export async function validateEmail({
	email,
}: {
	email: string;
}): Promise<boolean> {
	if (!email) {
		return false;
	}

	email = email.toLowerCase();

	email = email.replace(/\s/g, '');
	const emailPattern =
		/^[-!#$%&'*+\/0-9=?A-Z^_a-z`{|}~](\.?[-!#$%&'*+\/0-9=?A-Z^_a-z`{|}~])*@[a-zA-Z0-9](-*\.?[a-zA-Z0-9])*\.[a-zA-Z](-?[a-zA-Z0-9])+$/;

	if (!emailPattern.test(email)) {
		return false;
	}

	/**
	 * Check if the email contains more than 3 numeric characters. If it does, throw an error.
	 */
	if (email && (email.match(/\./g)?.length ?? 0) > 3) {
		return false;
	}

	/**
	 * Validate TLD
	 */
	const tld = (email: any) => email.split('@')[1].split('.').pop();
	if (!tlds.includes(tld(email))) {
		return false;
	}

	/**
	 * remove email modifier
	 */
	const atIndex = email.indexOf('@');
	const plusIndex = email.indexOf('+');
	if (
		plusIndex !== -1 &&
		plusIndex < atIndex &&
		process.env.NODE_ENV === 'production'
	) {
		email = email.slice(0, plusIndex) + email.slice(atIndex);
	}

	const [username, domain] = email.split('@');

	if (username.length < 3) {
		return false;
	}

	if (/^\d+$/.test(username)) {
		return false;
	}

	return dnsResolver(domain);
}

/**
 * This method validates all supplied email addresses.
 * @param {Array} mailingList array of email objects to be verified
 * @returns {Array} object consisting of valid and invalid email addresses { valid: [], invalid: [] }
 * @memberof Verymail
 * @example
 * const { data } = await validateEmailBulk(
 *   {
 *	    email: 'user1@example.com',
 *   },
 *   {
 *       email: 'user2@example.com',
 *   },
 * ])
 *
 */
export async function validateEmailBulk(mailingList: any[]) {
	try {
		let i;
		let ValidEmailList: any[] = [];
		let InValidEmailList: any[] = [];

		for (i in mailingList) {
			if (mailingList.hasOwnProperty(i)) {
				if (await validateEmail({ email: mailingList[i].email })) {
					ValidEmailList.push(mailingList[i]);
				} else {
					InValidEmailList.push(mailingList[i]);
				}
			}
		}

		return {
			valid: ValidEmailList,
			invalid: InValidEmailList,
		};
	} catch (error) {
		return { data: [] };
	}
}