We recently installed an additional MTA server into one of our infrastructures so now we have taken AS/AV loads off the main mailbox server. We wanted to enable archiving so we installed it on our main mailbox server. Curiously we had archiving working before on this infrastructure, and then we must have at some point failed to upgrade the archiving component and so it didn't appear as a service we could enable. During the last upgrade (to version 5.0.16) we once again installed the archive element to get archiving working again, although that didn't seem to do the trick. Do we also need to get it installed on the separate MTA server? Are there some additional steps we might have missed in doing this?