Add a received mail message in the listen func of mailRethinkDb.js

src/server/mail/mailRethinkDb.js

@@ -61,6 +61,12 @@ module.exports = {
 
 								sentMessages.push(r.msg);
 								delete r.msg;
+							} else {
+								player.social.notifySelf({
+									message: 'You have received a mail',
+									className: 'color-greenB',
+									subType: 'mail'
+								});
 							}
 
 							delete r.pos;