If you are migrating from one Microsoft Exchange server e.g. 1and1 or an inhouse Exchange server, to Office 365 your computer may hold onto the previous settings making it difficult to connect to your Office 365 Email account using Outlook. A number of things can happen like constantly asking for your password.
So how can we set up Outlook to point to your new Office 365 email account? Here are a number of suggestions.
First thing to do is to check that your settings are correct. Using tools like MXToolbox will confirm that your settings are correct. You can also ping your autodiscover cname.
Microsoft also provides a tool for troubleshooting - Microsoft Remote Connectivity Analyzer
Go to http://diagnostics.office.com/#/ and download and install the Office 365 Support and Recovery Assistant. Once downloaded click on the setup to run the program
Accept the license agreement
Click the 'Start' button.
Sign in using your email address and your Office 365 password and then click the 'Start' button.
Click on the 'Outlook' option and then click the 'Next' button.
Click on the 'I can't set up Outlook with my Office 365 account' option and then click the 'Next' button.
Select 'Yes' to 'Is this the affected machine' and then click the 'Next' button. The assistant will now run some tests
Click the 'Yes' button when asked to set up the Office 365 account.
Insert your profile name. This is a new profile in Outlook. Call it something like yournameemail-Office365 e.g. firstname.lastname@example.org-Office365. Then click the 'Next' button.
Login using the Office 365 email and password.
Your are now finished and Outlook will start with your Office 365 account. You can double check the settings via the Control Panel --> Mail (32 bit). Go to account settings and click on the 'Connection' tab and 'Exchange Proxy Settings'. The URl should be 'outlook.office365.com'