I am using the FQN of the server on the internet, but we want to keep the forms based authentication.
We wound up taking out a tech support incident with Microsoft and here is the answer that actually got up up and running.
There are 2 workarounds
1. Use a Front End
2. Create a second virtual directory for Exchange that does not require SSL and add a reg key. It looks like you have done this but
When you created the Exchdav virtual directory, did you create it through Exchange System Manager or Internet Services Manager?
This virtual directory needs to be created through Internet Services Manager for Exchange ActiveSync to work. Here are the steps to do this. Can you please try it and let me know how it goes.
If you are using Windows Server 2003 or later, follow these instructions:
1. Start Internet Information Services (IIS) Manager
2. Locate the \exchange virtual directory (default location is Web Sites\Default Web Site\Exchange)
3. Right click on the Exchange virtual directory, choose All Tasks à Save Configuration to a File...
4. Type a name in the File name: text box (for example, ExchangeVDir)
5. Click OK
6. Right click the root of this web site (Default Web Site), choose New à Virtual Directory (from file)...
7. On the Import Configuration dialog box, select the Browse button and locate the file from step #4, then click Open
8. Next, select the Read File button
9. In the Select a configuration to import text box, select Exchange (or whatever virtual directory you selected in step #3) and press OK.
10. A dialog box will appear stating the virtual directory already exists. In the Alias text box, type a name for the new virtual directory that you want the Exchange Server ActiveSync and Outlook Mobile Access processes to use. For example, type ExchDAV.
11. Click OK
12. Right click on the new virtual directory and choose Properties, in this example, ExchDAV
13. Select the Directory Security tab
14. Click the Edit button in the Authentication and access control section.
15. Verify only the following authentication methods are enabled
- Integrated Windows authentication
- Basic authentication
16. Click OK
17. Click Edit under IP address and domain name restrictions.
18. Click Denied access, and then click Add.
19. Click Single computer (if this option is not already selected), type the IP address of the server that you are configuring, and then click OK.
20. Click the Edit button in the Secure communications section
21. Verify Require secure channel (SSL) is not enabled and click OK.
22. Click OK, and then quit IIS Manager.
23. Click Start, click Run, type regedit in the Open box, and then click OK.
24. Locate the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MasSync\Parameters
25. Right-click Parameters, point to New, and then click String Value.
26. In the New Value #1 box, type ExchangeVDir, and then press ENTER.
27. Right-click ExchangeVDir, and then click Modify.
28. In the Value data box, type a forward slash ( /) followed by the name of the new virtual directory that you created in step 10. For example, type /ExchDAV.
29. Click OK, and then quit Registry Editor.
30. Restart the World Wide Web Publishing Service. To do this:
a. Click Start, click Run, type services.msc in the Open box, and then click OK.
b. In the Name list, right-click World Wide Web Publishing Service, and then click Restart.