客户端通过RPC连接邮件前端访问服务器，现在CAS和邮箱角色基本都是分离的。默认情况就是随机的。如果一个CAS服务器的邮箱数目较多，就会出现RPC服务死掉。那么outlook客户端就会出现未响应的状态。因此有时需要我们来为部分用户邮箱数据库指定CAS服务器。以下命令将更新邮箱数据库，以便数据库中的所有邮箱客户端连接通过客户端访问服务器或客户端访问服务器阵列。也可以使用此命令更改客户端用于连接邮箱服务器的客户端访问服务器或客户端访问服务器阵列。

Set-MailboxDatabase <Mailbox Database Name> -RpcClientAccessServer <ClientAccessServer or ClientAccessServerArrayID>

Using Exchange 2010 Management Shell:
Change RPCClientAccessServer Attribute to be FQDN of Exchange 2010 Mailbox Databases (repeat for all Databases on Exchange 2010)
Set-MailboxDatabase –Identity “<Database Name>” –RPCClientAccessServer “<servername>.<internaldomain>.local
Using Exchange 2010 or 2013 Management Shell:
Change SCP Object for Exchange 2010 to Point to Exchange 2013 (repeat for all Exchange 2010 CAS Servers); set this to whatever your internal AutoDiscover namespace is.
Set-ClientAccessServer –Identity “servername” –AutoDiscoverServiceInternalURI https://outlook.domain.com/autodiscover/autodiscover.xml
Using Exchange 2010 Management Console:
Set Exchange 2010 Outlook Anywhere to NTLM (repeat for all Exchange 2010 CAS servers)
EMC-Server Configuration-<servername>-Right Click-Properties-Outlook Anywhere Tab- Change Authentication method to “NTLM”
Using Exchange 2013 Management Shell:
Temporarily adjust Authentication Method on Exchange 2013 Outlook Anywhere to be NTLM (required for users on Exchange 2010)
Set-OutlookAnywhere -Identity “<exchange2013cas>\rpc (Default Web Site)” -InternalClientAuthenticationMethod:Ntlm -IISAuthenticationMethods Basic,Ntlm,Negotiate -SSLOffloading $false
Once Exchange 2010 has been removed and uninstalled, run the following command to reset authentication.
Using Exchange 2013 Management Shell:
Adjust Authentication Method on Exchange 2013 back to Negotiate
Set-OutlookAnywhere -Identity “<exchange2013cas>\rpc (Default Web Site)” -InternalClientAuthenticationMethod:Negotiate -InternalClientAuthenticationMethod:Ntlm -IISAuthenticationMethods Negotiate -SSLOffloading $false