Hello everyone, One user is sending an email to our mail server and keeps getting this back but he can send email to other people. I can't find any solution for it. Has anyone got a suggestion? Help is much appreciated Your message did not reach some or all of the intended recipients. The following recipient(s) could not be reached: username on 6/9/2006 5:54 PM This message could not be sent. Try sending the message again later, or contact your network administrator. The client operation failed. Error is [0x80004005-0x0004b9-0x000501].