use utils.toISOString

src/messaging.js

@@ -6,6 +6,7 @@ var db = require('./database'),
 	user = require('./user'),
 	plugins = require('./plugins'),
 	meta = require('./meta'),
+	utils = require('../public/src/utils'),
 	notifications = require('./notifications'),
 	userNotifications = require('./user/notifications');
 
@@ -128,7 +129,7 @@ var db = require('./database'),
 						var self = parseInt(message.fromuid, 10) === parseInt(fromuid, 10);
 						message.fromUser = self ? userData[0] : userData[1];
 						message.toUser = self ? userData[1] : userData[0];
-						message.timestampISO = new Date(parseInt(message.timestamp, 10)).toISOString();
+						message.timestampISO = utils.toISOString(message.timestamp);
 						message.self = self ? 1 : 0;
 						message.newSet = false;