(!) Solutions for the most common issues with Outlook are listed below. To help identify and solve your issue, try the Outlook connectivity troubleshooter and the Mail Flow Guided Walkthrough.
Some people who have been recently upgraded from the pre-upgrade version of Office 365, are having connectivity problems with Outlook. There are a few things that can cause issues. The most common cause seen by Support is an outdated operating system or software, so you should check that first. If that meets requirements, continue to go through the steps below in order. Test your Outlook connection between each step. If you've completed the steps below and are still having issues, post the details of your situation to this discussion in the Email and calendar forum.
Important: It may take over 48 hours to complete the upgrade of a particular tenant. If you have questions about your upgrade, see Office 365 Service Upgrade Center for Enterprise or Office 365 Service Upgrade Center for Small Business. If you have questions about what to expect while your tenant is being upgraded, read the Guide to the Office 365 Service Upgrade for 2013.
Step 1. Make sure that your operating system and software is up to date
Check the version of your software and your operating system to see if they meet the minimum requirements for Office 365. There’s a list of all the minimum software requirements located here. If the versions that you are using aren’t supported, you’ll need to upgrade. You can continue to send and receive email and manage your calendar and contacts in Outlook Web App.
If your operating system and software meet requirements, you might just need to install a software update for Outlook. Run Windows Update to install the latest patches and feature updates.
Step 2. Repairing your Outlook profile may resolve your connection issue
How do I repair my Outlook 2007 profile?
In Outlook 2007, on the Tools menu, click Account Settings.
In the Account Settings dialog box, on the E-mail tab, select your account, and then click Repair. Follow any prompts from the repair wizard.
When the repair is done, restart Outlook 2007.
How do I repair my Outlook 2010 or Outlook 2013 profile?
In Outlook 2010 (or Outlook 2013), on the File tab, click the arrow next to Account Settings, and then click Account Settings.
In the Account Settings dialog box, on the E-mail tab, select your account, and then click Repair. Follow any prompts from the repair wizard.
When the repair is done, restart Outlook 2010.
For more details on how to repair your Outlook profile including instructions for other Outlook clients go to
http://support.microsoft.com/kb/2847916.
Step 3. Verify Connectivity and Autodiscover settings
Use the Microsoft Remote Connectivity Analyzer to test Autodiscover for your account. If you have repaired your Outlook profile and are still experiencing issues, administrators can follow the directions in this link to correct the Autodiscover DNS settings. If you need help with this diagnostic tool, you can read more about how to use it for troubleshooting email problems here.
Step 4. Still having connectivity problems?
Have you tried the Outlook connectivity troubleshooter? This tool can help guide you through diagnosing and resolving Outlook issues.
If you have completed the steps above, but are still experiencing connectivity issues with Microsoft Outlook, please contact Support.
To submit a new service request or to find a phone number for your country or region, sign in to Office 365. On the Admin Overview page, on the left pane, under Support, click Overview.