Here is a document that is listed for this specific error 6287.
Unable to open items in shared mailboxes in an environment where more than one vault site is in use.
Details:
Situation:
If you have mailboxes on an Exchange server being archived by a Vault server (Vaultserver1) in a Vault Site (Site1) and some of these users have delegate access to mailboxes on a remote Exchange server being archived by a remote Vault server (Vaultserver2) in a different Vault Site (Site2), you may be unable to retrieve items from the remote server
The failure arises when double-clicking on an archived item. The above-mentioned event is logged on the Vault server.
Solution
Enterprise Vault 5:
To resolve this issue, assuming that the local client has permissions to access the delegate mailbox archive on the remote VERITAS Enterprise Vault (tm) server, add the WebAppURL setting to the desktopsettings.txt file on each Vault server pointing at the other Vault server.
Example:
Vaultserver1
WebAppURL[VaultSite2] = http:// Vaultserver2.evdomain.com/enterprisevault
Vaultserver2
WebAppURL[VaultSite1] = http:// Vaultserver1.evdomain.com/enterprisevault
where VaultSite is the name of the remote Enterprise Vault site, and the URL is the webapp url that you would normally use to access this vault site.
Enterprise Vault 6 and above:
Navigate to the mailbox policy settings for the webapp url as follows:
1. Expand 'Console Root' > Enterprise Vault > Directory on 'Servername' > Site name > Polices > Exchange > Mailbox
2. Double click on the exchange mailbox policy relevant to the users experiencing this issue
3. Select the 'Advanced' tab
4. Change the drop-down to Outlook/Desktop (depending on version)
5. Add an entry to 'Web Application URL' as follows:
Vaultserver1
[VaultSite2] = http:// Vaultserver2.evdomain.com/enterprisevault
Vaultserver2
[VaultSite1] = http:// Vaultserver1.evdomain.com/enterprisevault
where VaultSite is the name of the remote Enterprise Vault site, and the URL is the webapp url that you would normally use to access this vault site.
Once either the V5 or V6+ procedure is completed, a mailbox sync will need to be run to update the hidden message settings for the user, and then the user will need to re-start outlook for these new settings to take affect.
Judy