In our environment forest is like; domain.com(usa)a.domain.com(usa) b.domain.com(eng) c.domain.com(brazl) d.domain.com(china)Each location will have its own Exchange 2010.But when a mail was sent to a user on c.domain.com(brazil) from external,firstly a.domain.com(usa) exchange server will receive this message and send to brazil exchange server over our mpls network.Is it possible that when usa exchange receive a message for another location,can it send this message to brazil exchange over internet connection(site to site) But all other traffic (ad sync,mapi connections etc) will be over on standart mpls network.Can we sepereta this connections?

only hub-to-hub comminications use smtp 25 port right?So if i add a static route on a.domain.com exchange server,"if destionation is brazil and port is 25 then send it from sitetosite"will another exchange connection follow this route?is this scenario fit for me?

Exchange 2010 is using the AD site for routing, as how your topology works currently To change mail flow for the Brazil, you need the another SMTP name space, public IP address and MX for that domain as I know Resources: “Using Active Directory Sites for Routing” section in Understanding Message Routing Configure Internet Mail Flow Directly Through a Hub Transport ServerJames Luo TechNet Subscriber Support (http://technet.microsoft.com/en-us/subscriptions/ms788697.aspx) If you have any feedback on our support, please contact tngfb@microsoft.com