Some back story to these issues, a few days ago we changed web-hosts which were hosting our sites and along with that various MX/A/CNAME records that point to our internal server. - Of course OWA broke temporarily and so did emails whilst our MX records were not up to date.
This is now all resolved and OWA works without error internally and externally. However ActiveSync somehow stopped working, I fail to see how it's related but our iPhones no longer receive emails with the message "Unable to connect to server"
I got to the point where I rebuilt ActiveSync but from the countless tutorials, suggestions and answers I've read I'm getting more and more frustrated.
This ActiveSync error has changed at least 5 times but before I am now getting this:
Allow: OPTIONS, TRACE, GET, HEAD, POST
request-id: 15ba8193-b4e1-45e6-aa40-3adfb78dd917
X-TargetBEServer: m1.microtechs.co.uk
Public: OPTIONS, TRACE, GET, HEAD, POST
X-FEServer: M1
Content-Length: 0
Cache-Control: private
Date: Tue, 19 Nov 2013 10:10:24 GMT
Set-Cookie: X-BackEndCookie=S-1-5-21-536459249-845240443-4185325216-1229=u56Lnp2ejJqBnsrJnp7JzsfSy8qczdLLzM6b0p7Gz57SnJnImZzJysmdypyagYHOxtDOztDNz87M387Pxc3Pxc3L; expires=Tue, 19-Nov-2013 10:20:24 GMT; path=/Microsoft-Server-ActiveSync; secure; HttpOnly
Server: Microsoft-IIS/8.0
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET