I have found how mail flow works on Exchange 2013 which would be cloud to cas to mailbox. However, if the mx record is pointing to the cas server on a exchange 2013 server, which server redirects mail to a mailbox on exchange 2007?
Is it the CAS server or the mailbox server. From the stuff I am finding it looks like it goes from mailbox to mailbox. Is this true? I need to know the answer so that I can make sure my firewall is set up appropriately as we are moving our exchange environment from an old DC to a new DC and need to make sure I have the nescessary ports open. I am trying to figure out if port 25 is open between the two mailbox servers, the two CAS servers, or both. Please advise and or refer me to some documenation with this answer. Thanks in advance!
