Our Exchange 2010 Organization has Exchange servers deployed at multiple sites, AU, NZ and UK.
We recently deployed a Exchange 2013 CAS/MBX server in AU site. Our OWA was cutover from the AU EX2010 CAS server to this EX2013 box. The OWA is still published as MAIL.CONTOSO.COM. The EX2013 server does not hold any mailboxes.
After the cutover, we notice users with mailboxes on remote site Exchange 2010 servers are having problem to connect through Outlook Anywhere. OWA and ActiveSync work perfectly for those uses through MAIL.CONTOSO.COM which is hosted at AU site. However, AU mailbox Users does not have this problem. They can use Outlook Anywhere without any issues. Note their mailboxes are hosted on EX2010 server still.
I tried with TestExchangeConnectivity site and get RPC Proxy Ping failed error for NZ and UK mailbox users. In the mean time, on the Ex2013 server I see event source MSExchange Front End Proxy HTTP event 3005, it basic warns EX2013 has marked NZ and UK remote site EX2010 server as Unhealthy due to exception.
I then confirmed and tested with our network team that ports 6000-6005 and 443 between AU and NZ UK sites. There is no package been blocked or dropped and I can telnet to 6001 from AU EX2013 server to NZ and UK EX2010 servers fine.
I then notice people were mentioning about manually setting EXCH and EXPR value to msstd:mail.contoso.com as mentioned in this post http://social.technet.microsoft.com/Forums/exchange/en-US/728be9b1-4415-4df6-a997-5ecb9ded9a63/rpc-proxy-cant-be-pinged-20132010-coexistence-with-outlook-anywhere?forum=exchangesvrgeneral
But I suspect this is not relate to my case, as RPC Proxy works perfectly between the AU EX2013 and EX2010 server.
Any suggestions?