Rocket.Chat/app/lib/server/functions/notifications/email.js

import { Meteor } from 'meteor/meteor';
import { TAPi18n } from 'meteor/rocketchat:tap-i18n';
import s from 'underscore.string';
import { escapeHTML } from '@rocket.chat/string-helpers';

import * as Mailer from '../../../../mailer';
import { settings } from '../../../../settings';
import { roomTypes } from '../../../../utils';
import { metrics } from '../../../../metrics';
import { callbacks } from '../../../../callbacks';
import { getURL } from '../../../../utils/server';

let advice = '';
let goToMessage = '';
Meteor.startup(() => {
	settings.get('email_style', function() {
		goToMessage = Mailer.inlinecss('<p><a class=\'btn\' href="[room_path]">{Offline_Link_Message}</a></p>');
	});
	Mailer.getTemplate('Email_Footer_Direct_Reply', (value) => {
		advice = value;
	});
});

function getEmailContent({ message, user, room }) {
	const lng = (user && user.language) || settings.get('Language') || 'en';

	const roomName = escapeHTML(`#${ roomTypes.getRoomName(room.t, room) }`);
	const userName = escapeHTML(settings.get('UI_Use_Real_Name') ? message.u.name || message.u.username : message.u.username);

	const roomType = roomTypes.getConfig(room.t);

	const header = TAPi18n.__(!roomType.isGroupChat(room) ? 'User_sent_a_message_to_you' : 'User_sent_a_message_on_channel', {
		username: userName,
		channel: roomName,
		lng,
	});

	if (message.msg !== '') {
		if (!settings.get('Email_notification_show_message')) {
			return header;
		}

		let messageContent = escapeHTML(message.msg);

		if (message.t === 'e2e') {
			messageContent = TAPi18n.__('Encrypted_message', { lng });
		}

		message = callbacks.run('renderMessage', message);
		if (message.tokens && message.tokens.length > 0) {
			message.tokens.forEach((token) => {
				token.text = token.text.replace(/([^\$])(\$[^\$])/gm, '$1$$$2');
				messageContent = messageContent.replace(token.token, token.text);
			});
		}
		return `${ header }:<br/><br/>${ messageContent.replace(/\n/gm, '<br/>') }`;
	}

	if (message.file) {
		const fileHeader = TAPi18n.__(!roomType.isGroupChat(room) ? 'User_uploaded_a_file_to_you' : 'User_uploaded_a_file_on_channel', {
			username: userName,
			channel: roomName,
			lng,
		});

		if (!settings.get('Email_notification_show_message')) {
			return fileHeader;
		}

		let content = `${ escapeHTML(message.file.name) }`;

		if (message.attachments && message.attachments.length === 1 && message.attachments[0].description !== '') {
			content += `<br/><br/>${ escapeHTML(message.attachments[0].description) }`;
		}

		return `${ fileHeader }:<br/><br/>${ content }`;
	}

	if (!settings.get('Email_notification_show_message')) {
		return header;
	}

	if (Array.isArray(message.attachments) && message.attachments.length > 0) {
		const [attachment] = message.attachments;

		let content = '';

		if (attachment.title) {
			content += `${ escapeHTML(attachment.title) }<br/>`;
		}
		if (attachment.text) {
			content += `${ escapeHTML(attachment.text) }<br/>`;
		}

		return `${ header }:<br/><br/>${ content }`;
	}

	return header;
}

const getButtonUrl = (room, subscription, message) => {
	const path = `${ s.ltrim(roomTypes.getRelativePath(room.t, subscription), '/') }?msg=${ message._id }`;
	return getURL(path, {
		full: true,
		cloud: settings.get('Offline_Message_Use_DeepLink'),
		cloud_route: 'room',
		cloud_params: {
			rid: room._id,
			mid: message._id,
		},
	});
};

function generateNameEmail(name, email) {
	return `${ String(name).replace(/@/g, '%40').replace(/[<>,]/g, '') } <${ email }>`;
}

export function getEmailData({
	message,
	receiver,
	sender,
	subscription,
	room,
	emailAddress,
	hasMentionToUser,
}) {
	const username = settings.get('UI_Use_Real_Name') ? message.u.name || message.u.username : message.u.username;
	let subjectKey = 'Offline_Mention_All_Email';

	if (!roomTypes.getConfig(room.t).isGroupChat(room)) {
		subjectKey = 'Offline_DM_Email';
	} else if (hasMentionToUser) {
		subjectKey = 'Offline_Mention_Email';
	}

	const emailSubject = Mailer.replace(settings.get(subjectKey), {
		user: username,
		room: roomTypes.getRoomName(room.t, room),
	});
	const content = getEmailContent({
		message,
		user: receiver,
		room,
	});

	const room_path = getButtonUrl(room, subscription, message);

	const receiverName = settings.get('UI_Use_Real_Name')
		? receiver.name || receiver.username
		: receiver.username;

	const email = {
		from: generateNameEmail(username, settings.get('From_Email')),
		to: generateNameEmail(receiverName, emailAddress),
		subject: emailSubject,
		html: content + goToMessage + (settings.get('Direct_Reply_Enable') ? advice : ''),
		data: {
			room_path,
		},
		headers: {},
	};

	if (sender.emails?.length > 0 && settings.get('Add_Sender_To_ReplyTo')) {
		const [senderEmail] = sender.emails;
		email.headers['Reply-To'] = generateNameEmail(username, senderEmail.address);
	}

	// If direct reply enabled, email content with headers
	if (settings.get('Direct_Reply_Enable')) {
		const replyto = settings.get('Direct_Reply_ReplyTo') || settings.get('Direct_Reply_Username');

		// Reply-To header with format "username+messageId@domain"
		email.headers['Reply-To'] = `${ replyto.split('@')[0].split(settings.get('Direct_Reply_Separator'))[0] }${ settings.get('Direct_Reply_Separator') }${ message._id }@${ replyto.split('@')[1] }`;
	}

	metrics.notificationsSent.inc({ notification_type: 'email' });
	return email;
}

export function sendEmailFromData(data) {
	metrics.notificationsSent.inc({ notification_type: 'email' });
	return Mailer.send(data);
}

export function sendEmail({ message, user, subscription, room, emailAddress, hasMentionToUser }) {
	return sendEmailFromData(getEmailData({ message, user, subscription, room, emailAddress, hasMentionToUser }));
}

export function shouldNotifyEmail({
	disableAllMessageNotifications,
	statusConnection,
	emailNotifications,
	isHighlighted,
	hasMentionToUser,
	hasMentionToAll,
	hasReplyToThread,
	roomType,
	isThread,
}) {
	// email notifications are disabled globally
	if (!settings.get('Accounts_AllowEmailNotifications')) {
		return false;
	}

	// user/room preference to nothing
	if (emailNotifications === 'nothing') {
		return false;
	}

	// user connected (don't need to send him an email)
	if (statusConnection === 'online') {
		return false;
	}

	// no user or room preference
	if (emailNotifications == null) {
		if (disableAllMessageNotifications && !isHighlighted && !hasMentionToUser && !hasReplyToThread) {
			return false;
		}

		// default server preference is disabled
		if (settings.get('Accounts_Default_User_Preferences_emailNotificationMode') === 'nothing') {
			return false;
		}
	}

	return (roomType === 'd' || isHighlighted || emailNotifications === 'all' || hasMentionToUser || (!disableAllMessageNotifications && hasMentionToAll)) && (!isThread || hasReplyToThread);
}