Don't know about v11, but certainly in v10 all you see are the subject lines and message sizes. I think this is basically because Backup Exec uses a work around to backup the mailbox items, so as far as it is concerned they are basically just files, so all it sees is the subject line as the filename, and the file size. Things like senders address, sent/received date are all properties within the mail message itself, so can't be viewed.
Can but hope that v11 will have found a work around to make it easier, but I wouldn't bet on it, though there may be a new technology in v11 for mailbox backups (have a vague memory of hearing something), but I'm not certain and don't know any details.