If you are rolling out a migration for a company which is already using Autodiscover, or AutoDiscover aware clients, in their environments, but want this to also work for the migrated users without breaking current behaviour this can offer a challenge. That is, until you know how to release this simple registry change to update Autodiscover on a per user basis!
First you need an Autodiscover.xml file to direct the users to Office 365 and it should look like this:
<?xml version="1.0" encoding="utf-8" ?> <Autodiscover xmlns="http://schemas.microsoft.com/exchange/autodiscover/responseschema/2006"> <Response xmlns="http://schemas.microsoft.com/exchange/autodiscover/outlook/responseschema/2006a"> <Account> <AccountType>email</AccountType> <Action>redirectUrl</Action> <RedirectUrl>https://autodiscover-s.outlook.com/Autodiscover/Autodiscover.xml</RedirectUrl> </Account> </Response> </Autodiscover>
Once you have created this file, save it in a central location available to all of your users (or multiple locations available to all your users if required).
Next, you need to set a registry fix to tell Outlook where to look for AutoDiscover for your domain. For this purpose you need to create a new Registry Key at HKCU\Software\Microsoft\Office\16.0\Outlook\Autodiscover (for Outlook 2016. For Outlook 2013 change the 16.0 to 15.0).
The key needs to be a new String with the name being your mail domain, and the value the path to the autodiscover.xml you created earlier.
When you create a new Outlook profile for a user with an email address @yourcompany.com Outlook will look to your local autodiscover.xml to find the mail servers, and ignore any local DNS/SCP entries for AutoDiscover, leaving non-migrated users with their normal expected experience, and migrated users with the clean and easy experience of AutoDiscover to setup their clients.
If you experience inconsistent behaviour with the above settings you may need an additional value for PreferLocalXML set to true (see below).
Full information on the optional settings under the Autodiscover subkey are available here: https://support.microsoft.com/en-gb/kb/2212902