When I move a mailbox from a database on EX13MB1 to a database on EX13MB2 at the remote office email doesn't make it to the mailbox.  Outlook shows that it is connected but no email flows and I end up getting delayed delivery notices.

Here is the setup;

Main Office

• Third Party Email Filter - WebSense
• EX13CAS - Exchange 2013 Client Access Server running on Server 2012
• EX13DB1 - Exchange 2013 Database Server running on Server 2012
• Laptop running Windows 7 and Outlook 2013

Remote Office

• EX13DB2 - Exchange 2013 Database Server running on Server 2012

Everything works fine in the Main Office. 

Here is what I did after the main office was set up;

• Installed an Exchange Database Server (EX13DB2) in the remote office.
• Made sure it showed up in the ECP.
• Created a Database on EX13DB2.
• Moved a mailbox from EX13DB1 to the new database on EX13DB2.  (This works fine)
• Re-started Outlook.
• Outlook connects to the mailbox and doesn't show any errors.

All ports are open between the main office and the remote office.  All of the servers can ping every other server.

My question is;

Why can't email flow between the database servers?  What am I missing here?

Eric

A quick follow up:

I have confirmed that you need to have a CAG in each site with a mailbox server. So if your remote server does not have one, you will need to install the role somewhere. The servers also need direct access to a Global Catalog server.

However, it looks like I was making things up about the involvement of the Front End Transport Service. To deliver mail to another site, the transport service (on a mailbox server) will communicate directly with the transport service on a mailbox server in the correct site (exact specifics depend on whether a DAG is implemented).