If you use Office 365 and encounter an issues using your Hosted Exchange mailbox where Outlook tries to connect to your Outlook.com account by default instead of the mailbox @your-domain-name try making the following changes on your PC
Step x - Update Your Registry
1. Click Start > Run > Type "regedit" (without quotes) to open the Registry.
2. Locate and then select the following registry subkey: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\AutoDiscover
3. Add a DWORD Entry ExcludeExplicitO365Endpoint
4. Value 1
5. Close Registry
6. Create a new profile via Control Panel > Mail > Show Profiles > Add a New Profile