"Microsoft Exchange Server is unavailable" message when you try to start Outlook in Office 365 dedicated

Applies to: Microsoft Business Productivity Online DedicatedMicrosoft Exchange Online Dedicated

Symptoms


When you try to start Microsoft Outlook in Microsoft Office 365 dedicated, you experience one of the following symptoms.

Symptom 1

You receive a message that resembles the following:
Microsoft Exchange Server is unavailable

Symptom 2

Outlook starts in the Disconnected state. That is, the lower-right corner of the Outlook windows displays Disconnected.

Cause


There can be several different causes of this issue. For example, Outlook may be set up incorrectly. Or, there may be network connectivity issues.

Resolution


To resolve this issue, follow these steps:
  1. Diagnose client connectivity issues between a local client computer and an Exchange server by using the client version of the Microsoft Connectivity Analyzer Tool. To do this, follow these steps:
    1. Install the Microsoft Connectivity Analyzer Tool. To do this, go to the following Microsoft website:
      Click the Client tab, and then click Install Now.

      Note A video and written instructions about how to use this tool are available on this website.
    2. After you install the tool, select I can't log on with Office Outlook. For example, see the following screen shot:

    3. Enter your Simple Mail Transfer Protocol (SMTP) address and logon credentials when you are prompted to do this.
    4. View detailed results, or save the results to provide to Microsoft.
  2. If this issue occurs only for a single mailbox, and if you encounter no problems when you run the Microsoft Remote Connectivity Analyzer Tool, create a new Outlook profile. For more information about how to do this, click the following article number to view the article in the Microsoft Knowledge Base:
    829918 How to create and configure email profiles in Outlook
  3. If creating a new Outlook profile doesn't resolve this issue, or if multiple users are affected, collect the following information, and then contact Microsoft Online Service Support:
    • Does this issue occur in a specific office network segment or on a specific Exchange mailbox server? 

      If only some users are affected, try to identify common factors. For example, is it a specific office network segment or users on a specific Exchange mailbox server that are affected?  
    • How long has this issue been occurring?

      Determine how long this issue has been occurring and when it began.  
    • Who are the affected users? 

      List at least five users who are experiencing this issue. 
    • Collect the following information from an affected user:
      • Output from the ipconfig /all command
      • Output from the ping command from the client to the destination
      • Output from the tracert command from the client to the destination
      • Output from the telnet command from the client to the destination on ports 135 and 443 (The expected result is a blank screen that displays a flashing cursor.) 
      • Output from the Microsoft Remote Connectivity Analyzer Tool