Here is a great article on enabling, verifying and troubleshooting Exchange Outlook Anywhere http://www.exchange-genie.com/2008/02/configuring-outlook-anywhere-for-exchange-2007-sp1/

See this articel for publishing Outlook Anywhere with ISA Server 2006 http://www.msexchange.org/tutorials/Outlook-Anywhere-2007-ISA-Server-2006.html

Outlook Anywhere Troubleshooting Guideline

Collect info:

Is it a testing environment?
Is the testing client located in the domain when you tested it?
Where did you get the certificate for outlook anywhere, Microsoft CA?
Did you create CNAME record for your exchange server’s external hostname? If the external hostname is set differently with the FQDN of the exchange server

The steps to enable outlook anywhere:

1. Enable outlook from EMC, I suppose you’ve already done that.
2. Add certificate to “Default Web Site” in IIS. 
   1. Note the values of the “Subject” and “Subject Alternative Name” fields Right-click “Default Web Site”->”Directory Security”->”View Certificate” button“Details” tab->check those fields
   2. Notes: “Subject” shall be the same one as your external hostname
3. Check “RPC” Virtual Directory in IIS
   1. Launch IE
   2. Enter URL https://servername/rpc
   3. It shall prompt for credential, cancel it
   4. The content of webpage shall only contain the words “Error: Access is Denied”
4. Try to create mail profile for test user in the domain at first
   1. Notes: After autodicover mail profile has been created, go to the setting window of “Outlook Anywhere”, and check the “On fast networks, connect using HTTP first…”
      Check if outlook anywhere is working in the “Connection Status”

For verifying RPC connectivity

• Launch cmd
• Testing RPC Proxy Server [rpcping -t ncacn_http -s ExchServer -o RpcProxy=RPCProxyServer -P “user,domain,*” -I “user,domain,*” -H 1 -u 10 -a connect -F 3 -v 3 -E -R none]
  • Notes: It will prompt for password for exchange server first, and the password for RPCProxyServer
  • Notes: RPC Proxy Server will be your Client Access Server [CAS], does the CAS role and MBX role stay on one box?
• Testing backend port
  • For store: RpcPing –t ncacn_http –s ExchangeMBXServer -o RpcProxy=RpcProxyServer -P “user,domain,password” -I “user,domain,password” -H 1 –F 3 –a connect –u 10 –v 3 –e 6001
  • For DSProxy: RpcPing –t ncacn_http –s ExchangeMBXServer -o RpcProxy=RpcProxyServer -P “user,domain,password” -I “user,domain,password” -H 1 –F 3 –a connect –u 10 –v 3 –e 6004