Set up @cam subdomain mailbox

How to set up your Exchange Online mailbox with an @cam subdomain email address, e.g. @botolphs.cam.ac.uk using the Outlook Windows desktop client.

1. If you haven't already done so, download and run this configuration script:

   ExchangeOnline.msi

   See instructions for: First-time Outlook set up | Existing Outlook users
    

2. With Outlook closed, open regedit and  browse to:

   HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0(or 15.0 for 2013 etc)\Outlook\AutoDiscover
    

3. Copy the cam.ac.uk registry string’s value data
    
4. Create a new string value (right click > new > string value) and name it the domain you want e.g. botolphs.cam.ac.uk
    
5. Right click on the created string and choose Modify
    
6. Paste the value data into the value data field
    
7. This should now work and follow your roaming profile around.

Registry key needed for each domain

You'll need a key for each domain. For example if I had an @lib.cam.ac.uk shared mailbox but my main mailbox was @cam.ac.uk, I'd need two registry keys.

DO NOT delete your @cam registry key.