Users cannot access email when VPN connection drops

I have two servers, both running Windows Server 2003 and Exchange Server 2003. ServerA is in SiteA and ServerB in SiteB. By SiteA and SiteB I am not only referring to two physical sites but also two AD sites. My two sites are connected by a VPN tunnel.

Both servers are domain controllers for the same domain and I recently enabled Global Catalog on ServerB.

Can anybody explain why, when the VPN connection drops, which it does occasionally, that none of the users in SiteB can access their mailboxes which are on ServerB?

Is this by design or is there a misconfiguration? Should the users in SiteB still be able to access their mailboxes on ServerB without the need for access to ServerA?
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

when the VPN connection drops, are all the exchange services on serverB running?
are the stores mounted on serverB at that time?
any errors in the application logs on serverB when the vpn connection drops?
infologicitAuthor Commented:
Hi rakeshmiglani
All the Exchange Server services are running on ServerB, all the stores are mounted on ServerB at the time the connection drops and there are no errors in the Application Log on ServerB during the time the VPN connection is down.
what error do the users get when they try to access their mailboxes when the vpn connection is down?
Do you have a replica of your public and system folders on Exchange is Site B?

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.