Hi Guys,

Am having issues with our exchange server, some of the staffs are not able to open mails through outlook or webaccess (OWA), in the exchange logs i found below  

"Cannot open mailbox /o=First Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=MAILBOX01/cn=Microsoft System Attendant"

We are running exchange 2010 with Hub Transport,CAS and Mailbox server role with 3 Domain controllers.

We have only two users with this problem, we had the past 3 month for another user but when we did a reboot it worked. Now we cant keep rebooting to solve this issue.

Please assist .

regards

Raymond

Hi,

Here is my suggestion below, could you please follow the steps to check the result?

1. In the ADSIEDIT, please locate the following path, then please check whether the Home MDB value is correct.

CN=Configuration,CN=Services,CN=Microsoft Exchange,CN=<org name>,CN=Administrative Groups,CN=Exchange Administrative Group (FYDIBOHF23SPDLT) ,CN=Servers,CN=<servername>,CN=Microsoft System Attendant Home MDB

2. If the value is incorrect, please locate the following path, then please copy the value and past in CN=Microsoft System Attendant Home MDB.

CN=Configuration,CN=Services,CN=Microsoft Exchange,CN=<org name>,CN=Administrative Groups,CN=Exchange Administrative Group (FYDIBOHF23SPDLT)  ,CN=Databases,CN=<DatabaseName>

3. Please reboot the Exchange server.

A related article for your reference:

The System Attendant homeMDB attribute is missing
http://technet.microsoft.com/en-us/library/dd535374(v=exchg.80).aspx

Best regards,
Belinda

If it is Exchange 2013, make sure your default mailbox is mounted. mine case error was appearing when creating public folder and that public folder mailbox is link with default mailbox. I have found out that mailbox datbaase was not mounted. i just mounted and above error disappear. 

Why mailbox database is not mounted. 

Make sure you have no limitation or mail box database was corrupted.