To help administrators with the remote connectivity to Exchange, Microsoft has created a website which will definitly help with troubleshooting remote connectivity issues. The great thing is that the website acts like a client (Outlook or Mobile) trying to connect to Exchange through SRV records (_autodiscover._tcp.domain.com) and autodiscover (among other things).

These tests include :

• Microsoft Exchange ActiveSync Connectivity Tests
  Exchange ActiveSync with AutoDiscover
  Exchange ActiveSync
• Microsoft Exchange Web Services Connectivity Tests
  ActiveSync Provider AutoDiscover
  Outlook Provider AutoDiscover
• Microsoft Office Outlook Connectivity Tests
  Outlook Anywhere with AutoDiscover
  Outlook 2003 RPC/HTTP 
• Internet Email Tests
  Inbound SMTP Email Test

View the website : Test Exchange Connectivity