I have two related companies--one in Europe, one in USA--each with their own AD domain, that use the same email domain. Both companies currently have Exchange 2007 in-house, and I'm looking to migrate to Exchange 2013.
Company USA:
Internal AD domain: USAcorp.local
Email domain: company.com
Company Europe:
Internal AD domain: Eurocorp.local
Email domain: company.com
Eurocorp has its Exchange server in a third domain, EuroExch.local, but that might be because they've set it up as a DMZ/perimeter network. My understanding is this won't work with 2013, so I'm planning on joining the new Exch2013 server to the Eurocorp.local domain.
THE CURRENT SETUP:
There is a spam filter that accepts all emails (MX records point to it) and filters out spam. It also rejects email to any recipients not on a manually-maintained recipient list. Approved messages go to USAcorp's Exchange server. Recipients not on the USA GAL get sent to Eurocorp's server.
AUTODISCOVER:
Autodiscover works for both sites, but it can be troublesome, and intermittently gives certificate errors. Exchange 2013 seems to rely more on autodiscover and I'm concerned we have a bad setup now that will be exposed with the migration. DNS records are:
MX: spamfilter.company.com (US) 100.100.100.1
A: email.company.com (US) 100.100.100.2
A: webmail.company.com (Euro) 200.200.200.1
SRV: _autodiscover._tcp.company.com webmail.company.com (Euro)
USAcorp has an internal DNS record for autodiscover pointing to the internal Exchange07 IP address, and this seems to work for the clients (will this cause problems with Exchange 2013?). Setting up internal DNS for Eurocorp autodiscover on Eurocorp's DNS server didn't seem to work. They claimed they were getting certificate notices for email.company.com (US), but they had a consultant who seemed hesitant to use anything but the SRV record.
QUESTIONS:
Is the current method of having each site house a CAS/Mailbox server, and routing mail to Euro clients via GAL the best way to go with Exchange 2013?
What's the best way to handle autodiscover, given that clients from both companies need autodiscover to point them to different Exchange servers (100.100.100.2 vs 200.200.200.1)?
Thanks in advance