While installing Exchange 2010, you may find setup failing part way, complaining about having no more endpoint mappers (taken from ExchangeSetupLog):

[Timestamp] [1] 0. ErrorRecord: There are no more endpoints available from the endpoint mapper. (Exception from HRESULT: 0x800706D9)[Timestamp] [1] 0. ErrorRecord: System.Runtime.InteropServices.COMException (0x800706D9): There are no more endpoints available from the endpoint mapper. (Exception from HRESULT: 0x800706D9)

Many organisations have their custom Windows builds which they generally automate, customise and harden.  If such builds have “Windows Firewall” and “Base Filtering Engine” services set to “Manual” or “Disabled”, it will very likely cause the failure mentioned above.  These services are required for a successful Exchange 2010 installation.

So, the solution is simple: Exit setup.  Set both services mentioned to “Automatic” and restart the server.  Restart setup.  Setup keeps track of installation progress all the way through so it will resume from where it was interrupted.  Just select the required roles again and follow general prompts to continue the install.

Additional Point: Enabling these services also prevent other problems later: Publishing Outlook Anywhere via TMG also requires these services to be enabled.  Otherwise, it also fails with a similar error message as mentioned above.

Hope this helps!