Hi AllWe are experiencing a strange error with our mail system. Every now and then, a certain user will not be able to send emails to a domain. She recv'sYou do not have permission to send to this recipient. For assistance, contact your system administrator. MSEXCH:MSExchangeIS:/DC=com/DC=kam/DC=emea:Exch1Our email flow is:Outlook > Exchange > MAIL RELAYS > InternetGiven that the NDR is from our Exchange, not our Mail Relay, this looks like an Exchange issue on our side, but not sure even where to start since it is only intermittent? She tried resending the message today and it worked?

Hi, Please first raise the diagnostics logging level on the MSExchangeTransport service based on the below link: For Exchange 20003http://technet.microsoft.com/en-us/library/aa996402(EXCHG.65).aspx For Exchange 2007http://technet.microsoft.com/en-us/library/bb201668(EXCHG.80).aspx Then check whether any error message come up in the event log when this issue reoccurs. Additionally, we can also enable message tracking log to help us examine this issue more clearly. And when happens again, please send the log to me at v-allson@microsoft.com Thanks Allen

Sheen,You can use registry for enabling diagnostic loggin in Exchange 2003.HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeTransport\Diagnosticand then set all the right hand side values to 7 (7 = expert loggin) and reproduce the issue or wait for the issue (ensure you do have enough space available to handle the event strom after enabling diagnostic loggin to 7)How to Set the Diagnostics Logging Level for MSExchangeTransport Categories to Field Engineeringhttp://technet.microsoft.com/en-us/library/aa997825(EXCHG.65).aspxYou can use the following step to set the diagnostic loggin for Exchange 2007 Server.How to Change Logging Levels for Exchange Processeshttp://technet.microsoft.com/en-us/library/bb201670.aspxHow to Configure Protocol Logginghttp://technet.microsoft.com/en-us/library/bb124531.aspxArun Kumar | MCSE - 2K3 + Messaging | ITIL-F V3

Hi AnilWe have not managed to replicate the issue, so I guess I will have to wait until we can try your steps.Thanks anyway!