Notes mail Routiniong Question

Dear All,I have a question regarding Notes mail routing.

I have a four server SRV-A SRV-B SRV-C SRV-D

Now SRV-A is a server in Head office SRV-B, SRV-C and SRV-D are servers in branch offices in same Domino Domain.

Users on SRV-B wants to sends mail to users on SRV-D and SRV-C . and there is no direct connectivity between branch office servers.

All branch office servers can connect with SRV-A but not with each other.

Now question is how this is possible that SRV-A receive mails of all the branch office servers and distribute to concerned servers.

Remember all servers are on same domino domain.

Please help

Thanks

Subject: Check Administrator Help

In the Contents view of Domino Administator Help, go to Mail > Planning a mail routing topology > The Domino mail router. Click the ‘Overview of routing mail using Notes routing’ link at the bottom of the ‘The Domino mail router’ document.

This document explains how mail is routed depending on whether servers are in the same Domino Domain and/or the same Notes Named Network.

Subject: No Major clue found from admin help

I setup local area network mail connection between each branch office and head office.

But problem is that branch office servers cannot send mail using head office server .

But if they have direct connectivity then they can send mail

I want to setup mail routing in such a way that if branch office servers need to exchange mail then mail routing should be done through head office servers.

Looking forward for your support and help.

Subject: Which scenario applies?

Which scenario described in the Help document I referenced applies to you?