I have been migrating many clients over to Office 365 lately. Every so often Outlook will have a problem making the initial connection.
Microsoft has created a nice tool that can fix many of the issues.
It's worth a shot. The free download is available at this link
HTTPS://diagnostics.office.com
IT Fixed it for me many times so far.
Labels: Itfixed it for me, Microsoft, Office 365, tools, Windows Utilities