Hi, Our scenario is multi-site locations with existing Exchange 2003 & 2007 with Outlook & Entourage clients. Currently there are more Exchange 2007 servers and few Exchnage 2007 servers & we are in process of upgrading/redesigning the infra. We have gone for CCR & CAS/HUB NLB at every site - considering not-so-good bandwidth & high availability requirements. CAS/HUB Scenario for every site is as follows, for an instance: Already existing CAS/HUB/MBX server: CASHUBMAIL (IP - 10.0.3.7) New CAS/HUB in NLB: Hostname 1 = CASHUB1: IP1 – 10.0.3.8 IP2 – 10.0.3.11 (NLB Node – without gateway & DNS) Hostname 2 = CASHUB2: IP1 – 10.0.3.9 IP2 – 10.0.3.12 (NLB Node – without gateway & DNS) A Record = PQRMAIL: 10.0.3.10 (This is the NLB cluster IP) A Record = MAIL: This is published on internet as MAIL.ABC.COM and internally it points to CASHUBMAIL via DNS A record. Problem Scenario: Existing Exchnage 2007 servers are SP1 versions and installed on Windows Server 2003. The new servers where we are migrating the mailboxes are Exchnage 2007 SP3 servers on Windows Server 2008 R2. Existing Entourage clients are configured to point to mail.ABC.com. When we migrate their mailbox, the mailbox is moved to the CCR server. To the surprise, Entourage client doesn’t work with Exchange entry pointing to mail.ABC.com. If I change it to PQRMAIL.ABC.com, it works. Does this mean CAS proxying is not working? Note that our new CAS/HUB servers doesn’t have any cert as yet (we are yet to add the FQDNs into existing SAN certificate) & we get an error for it as well. Secondly, its found that for the new configuration of Entourage profile, where we configure a mailbox for a destination mailbox (on Exchange 2007 SP3 CCR), it works only with PQRMAIL.ABC.com & not with mail.ABC.com. Why? No idea… Again looks like proxying is not working… Thirdly, there is a beta Outlook 2011 for Mac rolled out. The mailboxes before migration are configured to https://CASHUBMAIL.ABC.COM/EWS/Exchange.asmx. When we migrate them, the new mailbox still points to the same address. If we change the address to https://PQRMAIL.ABC.COM/EWS/Exchange.asmx and close & open the Outlook for Mac, it switches back to https://CASHUBMAIL.ABC.COM/EWS/Exchange.asmx. I dont know why. p.s. our source servers are Exchange 2007 SP1 & destination servers are Exchange 2007 SP3. Source servers are also Exchange 2003. p.p.s. Above example is for one of the sites in our infrastructure and all servers mentioned are from the same site. Kindly suggest/assist. Regards, Harish Harry