Anyone seen this (or something similar) before? A user receives this NDR after they accept a meeting request. The NDR is on the Accept response: This message could not be sent. Try sending the message again later, or contact your network administrator. The client operation failed. Error is [0x80004005-0x000456-0x000501]. The strange thing is after opening the NDR and clicking send again that response works. Also after doing that new meeting request responses now works are well... Difficult to troubleshoot a moving target... ________________________________ Frank Wakelin Network Analyst direct tel.: 604.640.4096 fax: 604.622.5911 fwakelin@xxxxxxxxxxxxx <http://www.blgcanada.com/nav/mainLogo.gif> Borden Ladner Gervais LLP 1200 Waterfront Centre 200 Burrard Street, P.O. Box 48600 Vancouver, B.C., Canada V7X 1T2 www.blgcanada.com <http://www.blgcanada.com/> WE INTEND THIS ELECTRONIC MAIL MESSAGE ONLY FOR THE PERSON OR ENTITY NAMED IN THE ADDRESSEE FIELD. THIS MESSAGE MAY CONTAIN INFORMATION THAT IS PRIVILEGED, CONFIDENTIAL OR EXEMPT FROM DISCLOSURE UNDER APPLICABLE LAW. IF YOU ARE NOT THE ADDRESSEE OR AN EMPLOYEE OR AGENT RESPONSIBLE FOR DELIVERING THIS MESSAGE TO THE ADDRESSEE, PLEASE NOTIFY US IMMEDIATELY BY TELEPHONE, PERMANENTLY DESTROY ANY COPIES YOU MAY HAVE AND RETURN THIS DOCUMENT TO US AT OUR EXPENSE AT THE E-MAIL ADDRESS NOTED ABOVE. ANY DISSEMINATION OR COPYING OF THIS MESSAGE BY ANYONE OTHER THAN THE ADDRESSEE IS STRICTLY PROHIBITED. WARNING: EMAIL MAY NOT BE SECURE UNLESS PROPERLY ENCRYPTED.