Generic Mailboxes and Enterprise Vault
Folder Level access can be a bit trick in Enterprise Vault. Depending on how your environment is set up you may run into this issue.
Non owner’s users who operate shared mailboxes are unable to open Enterprise Vault Items. Users will see the following error “You do not have access to this vault.” although they have folder level access to the mailbox and are able to see the EV item.
Default or Anonymous permissions have been used in order to grant the users access to the mailbox folder.
Grant each user permissions to a mailbox folder. Users will then receive access to Enterprise Vault Items.