let's say there's a company called "Contoso" which has 200 employees in Germany and 200 in the U.S.. They share the same Maildomain @contoso.com and are currently using 1 on-premises Exchange Server deployment in Germany. U.S. Site is connected via S2S-VPN and they use also just 1 AD (contoso.com) with 2 sites.
They now want to move to Office 365 E3 (or maybe even E5 due to S4B).
As there's just 1 AD I can setup just 1 O365 subscription, right?
So if I subscribe to O365 with location Europe/Germany (I am NOT talking about MS German Cloud), how can I accomodate the U.S. mailboxes with fast access? Having them to connect to Europe might have a performance impact, doesn't it? I can set "location" for the U.S. mailboxes to "United States" but as far as I know this does not have impact on the location where the mailbox ist stored, or?