Error Message

Final error: 0xe00003bf  -  Cannot open one or more mail messages because of unknown Exchange Web Service errors. Review the job log for more information.
Final error category: Resource Errors

Restore- \\Exchange SERVERNAME\Microsoft Information Store\MailboxDB Name

V-79-57344-959 - Unable to open the item Database - skipped

OR

The following can be seen in SGMON results:
58] [17508]     2012-10-22T13:21:57.721 [fsys\mb2]           - SendSeedMSG: Faied on remote server 80004003.
BEREMOTE: [10/22/12 13:21:58] [17508]     2012-10-22T13:21:57.721 [fsys\mb2]           - SendSeedMSG FAILED! RC = 0x00000000
MONAD:    [10/22/12 13:21:57] [0000]     [1] []  BEExch2007Component::ValidCredentials

BEREMOTE: [10/22/12 13:21:59] [17508]     2012-10-22T13:21:58.766 [fsys\mb2]           - CreateMessage failed for e_id->len = 70, msg with 80004005
BEREMOTE: [10/22/12 13:21:59] [17508]     2012-10-22T13:21:58.766 [ndmp\loops]         - Error: OpenObj returns extended error e00003bf
BEREMOTE: [10/22/12 13:21:59] [17508]     2012-10-22T13:21:58.766 [ndmp]               + rest_obj.cpp (1853):
BEREMOTE: [10/22/12 13:21:59] [17508]     2012-10-22T13:21:58.766 [ndmp]               | OpenObj returned FS_EXTENDED_ERROR with unexpected action code: 2. Early return.

EWSDebug
13:21:57  Exception in FindFolder The request failed. The underlying connection was closed: An unexpected error occurred on a send.

Cause 1:

During the restore process Backup Exec tries to establish Exchange Web Services (EWS) connection on the mailbox server instead of the Client Access Server (CAS) which results in the failure.

The errors shown above in SGMON and EWSDebug occur if the Client Access Server (CAS) resolves to IPv6 when attempting to ping localhost.
To confirm: Run the following command on the Exchange CAS:  ping localhost
Check if it returns an IPV6 value like ::1

Caues 2:

Administrator account mailbox exists in an earlier version of Exchange server when using an environment with mixed Exchange versions.

Cause 2:

Move the administrator's mailbox to the latest version of Exchange server or create new administrator user and mailbox in the latest version of Exchange server.