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Summary: Outlook’s connection to Exchange Server can be interrupted by the ‘Exchange Server is Unavailable’ error. Causes include server downtime, third-party apps, and add-ons. Solutions range from restarting server services to registry edits, cache resets, or converting OST to PST for uninterrupted email communication.

When Outlook is successfully connected to the Exchange Server, it will display the status as ‘Connected to: Microsoft Exchange,’ ensuring seamless email communication. However, in certain situations, when the Exchange Server becomes unavailable, it may generate an error message stating

‘The connection to Exchange Server is unavailable.’

This error can be particularly troublesome because it prevents you from accessing your mailbox and sending or receiving emails. Occasionally, the issue may arise due to an unstable internet connection and can often be resolved by re-establishing a stable connection. However, if the error persists, it’s essential to explore various troubleshooting methods tailored to the specific root cause of the problem.

What causes error “Exchange Server is Unavailable”?

The Exchange Server is down

Encountering an error in Outlook doesn’t always imply a fault on your end; it could be due to an issue with the Exchange Server being temporarily unavailable. In such cases, you can simply wait for the server to resume normal operation.

Third-party applications are stopping Outlook

Numerous third-party applications, such as anti-malware and monitoring tools, have the capability to monitor and potentially interfere with the functioning of other applications. Occasionally, your system’s anti-malware software might inadvertently disrupt Outlook’s operation.

Faulty add-ons in Outlook

Outlook incorporates various add-ons designed to enhance its functionality, such as grammar checking and PDF conversion tools. Since these add-ons often come from external sources, they can have an impact on Outlook’s performance and potentially disrupt its connection with the Exchange Server.

Fix the error “Exchange Server is Unavailable”

There are several manual solutions available to address this error. Let’s explore some of them:

By Restarting the Exchange Server services.

If the connection between the Exchange Server and Outlook is interrupted due to service inactivity, you can restore it by restarting the service, thereby re-establishing the connection.

  1. Go to the Windows Server menu, click Run, and input services.msc command. Then click Enter.
  2. After opening the list of all the services, locate the Exchange services and restart them.
By changing the permission level of data files

Data files on the system, like any other files, have permission levels such as Write and Read-only. If the permission levels for the data files have been inadvertently set to Read-only, you can rectify this by restoring them to the Write permission level.

  1. Locate the data files from their respective locations. Generally, the data files are present in the Microsoft Outlook folder in the App data folder in C drive.
  2. Choose the data file of the Outlook account that you are currently using. Right-click and check its Properties.
  3. If it shows Read-only, then uncheck it and check the other option to Write.
  4. Now Restart Outlook.
Editing Registry Values

Incorrect registry settings can be a reason for the error “Exchange Server is Unavailable.” To fix this issue, you need to modify it. Follow the steps to edit the registry values:

  1. Press Windows+R, type Regedit and click OK.
  2. Editing Registry Values

  3. Click Yes button on permission box. Then a Registry Editor window will get opened. In it, find HKEY_CURRENT_USER and then select Software in it.
  4. Registry Editor  window

  5. Now, navigate to Microsoft>Office>Outlook>RPC.
  6. On File, go to Edit, click New > DWORD.
  7. Type DefConnectOpts and press Enter.
  8. Right-click DefConnectOpts and click Modify. Give it value 0 and click OK.

Thus, the registry value has been modified.

Through Cache Resetting

The ‘Exchange unavailable’ error can sometimes be attributed to outdated storage data in the cache. You can address this issue by executing the ‘flushdns’ command, which will automatically remove the outdated information by resetting the DNS cache server.

In Command Prompt (as administrator), run: ipconfig/flushdns
After the execution, close the Command Prompt. Then, try to connect Exchange Server once again.

With Third-Party Professional Software

When you encounter the ‘Exchange Server is Unavailable’ error, your email activities may be disrupted. However, you have the option to convert OST files to PST format and use them in Outlook to re-establish email communication. This conversion process can be accomplished using tools like Kernel for OST to PST.

When you need to transfer OST data to different platforms, the OST to PST converter tool remains a versatile solution. This software facilitates the conversion of Outlook OST emails to PST, Office 365, and Exchange, making it suitable for various scenarios. It can effectively convert orphaned or corrupted OST files while ensuring data integrity and security. Noteworthy features of the software include intelligent filters, multiple destination options, and an intuitive user interface.

Kernel for OST to PST