We are seeing some weird behaviour on our exchange 2013 environment.

We have had Exchange up and running for over a year now with very little issue, currently on CU6. However in the last couple of weeks we have seen some issues with Autodiscover. It appears only to affect external users whose email address match their UPN, ie. Users who use an email alias of a different domain seem not to be affected.

User UPN - @companya.org.uk

Autodicover using @companya.org.uk fails

Autodiscover using @company.com works

There have been no changes to our autodiscover or DNS. After some extensive testing I have narrowed it down that only Outlook 2013 clients seem to be affected. So I brought up fiddler and noticed that when using the affected domain to try and autodiscover the request was then being routed to ActiveSync URL rather than the Outlook Anywhere URL. So further investigation of the Autodiscover logs it seems that users with the most recent Office client updates seem to be sending a different Useragent string than those without the November updates.

Pre November 2014 office update user agent string- Microsoft Office/15.0 (Windows NT 6.1; Microsoft Outlook 15.0.4667; Pro)

After November 2014 office update user agent string - Outlook/15.0 (15.0.4667.1000; MSI; x86)

I have proved there to be an issue as I uninstalled Outlook from my machine and reinstalled RTM with no updates and autodiscover works fine.

Is it possible that this changed user agent string is stopping exchange recognising that Outlook should use Outlook Anywhere? And even if that is the case why it only happens when using the UPN domain for autodiscover? Has anyone else seen this issue with the latest Office updates?

• Edited by scotta001 Thursday, November 27, 2014 1:04 PM Typo

In case anyone else is having this issue, after working with Microsoft they have confirmed KB2899504 & KB2986204 are the culprits behind this and that there should be a fix in place by the end of February.

• Marked as answer by scotta001 Monday, January 05, 2015 10:40 AM

In case anyone else is having this issue, after working with Microsoft they have confirmed KB2899504 & KB2986204 are the culprits behind this and that there should be a fix in place by the end of February.

• Marked as answer by scotta001 Monday, January 05, 2015 10:40 AM
• Unmarked as answer by scotta001 22 hours 0 minutes ago

In case anyone else is having this issue, after working with Microsoft they have confirmed KB2899504 & KB2986204 are the culprits behind this and that there should be a fix in place by the end of February.

• Marked as answer by scotta001 Monday, January 05, 2015 10:40 AM
• Unmarked as answer by scotta001 Wednesday, April 01, 2015 9:24 AM

So it appears that this still has not been resolved, we have a case open with MS again to investigate. I will update, once we have heard.

• Edited by scotta001 17 hours 33 minutes ago typo

So it appears that this still has not been resolved, we have a case open with MS again to investigate. I will update, once we have heard.

• Edited by scotta001 Wednesday, April 01, 2015 1:51 PM typo

So we have had it confirmed from Microsoft, this is fixed with KB3054855. We have tested and can confirm it has resolved the issue.

https://support.microsoft.com/en-us/kb/3054855

• Marked as answer by scotta001 Friday, June 19, 2015 3:51 PM