Architecture question related to licensing

[Brutus I]

We have two locations each with a Zimbra server. Site A is running the latest ZCS NE and has plenty of extra licenses. We are hosting email on this server for some of our customers. Site B server is running the open source edition and hosting our internal email. We would like to get on network edition but are too small to justify purchasing a separate block of licenses for that server. We could migrate to the hosting server but don't want to be in a position that anything taking out our customers email at Site A would also take out ours and make it more difficult to contact us.

Is it possible to do a multi-server setup that would keep our email on a box at Site B but still make use of the additional licenses installed on the server at Site A (the two locations are on site to site vpn)? If so could someone give me a brief big picture overview of how such a setup would work? I've looked over the multi-site install doc but still not clear if and how we can achieve the above.

[bdial]

what you would do is add another mailbox server to the NE setup of site a, but this mailbox server would be located at site b. you can specify by cos which server users should be created on, and they'll use that server to access their e-mail.

you should also consider putting an ldap replica at siteb as well, because if you don't then all ldap requests have to go across the wan or whatever you have, and if the link goes down people will be unable to authenticate. you could do a mta setup down there too it depends on how complex you want to go

[Brutus I]

If I'm understanding correctly without MTA at site B the inbound and outbound mail would flow through the server at site A? Also is it possible to have the mail store to replicate to both servers as a fail over or can a mailbox only reside on one server?

[bdial]

you're correct about the mta.

replication is not possible right now.