Outlook Constantly Prompts for Password When Connecting to Microsoft 365
In this article, we will cover:
– Symptoms
– Causes
– Solution
– Additional Information
Symptoms
When you try to create an Outlook profile or connect to a Microsoft 365 mailbox, you are repeatedly prompted for your credentials. Meanwhile, the client shows the message “attempting to connect…”. If you cancel the prompt, you receive the following error message:
– “The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.”
Causes
This issue can occur if the “Logon network security” setting on the “Security” tab of the Microsoft Exchange dialog box is set to a value other than “Anonymous Authentication”.
The screenshot shows the “Security” tab in the Microsoft Exchange dialog box, verifying if the “Anonymous Authentication” value is set for logon network security.
Solution
Note: In Microsoft Outlook 2016 and some of the latest builds of Outlook 2013, this issue does not occur. These versions have been updated to prevent the problem described in the “Symptoms” section. In these versions, the “Logon network security” setting is either disabled or removed from the Microsoft Exchange email account settings.
For Newer Versions of Outlook
Run the self-diagnosis tool:
If you are a Microsoft 365 customer and encounter the error described in the “Symptoms” section when connecting to an Exchange Online mailbox using newer versions of Outlook 2013 or Outlook 2016, you can run diagnostics to identify the issue. The diagnostics will perform automatic checks and provide possible solutions for the detected problem. Download the Microsoft Support and Recovery Assistant app, and after installation, you will be prompted to sign in to your Microsoft 365 account. Then select “Advanced Diagnostics” to run the diagnostics.
For Older Versions of Outlook
If you have an older version of Outlook, change the “Logon network security” setting to “Anonymous Authentication” to resolve this issue. Follow these steps:
1. Close the Outlook application.
2. Open the Control Panel and do one of the following:
– In Windows 10, Windows 8.1, or Windows 7, click Start, type “Control Panel” in the search box, and press Enter.
– In Windows 8, swipe in from the right to open the charms, tap or click Search, then type “Control Panel” in the search box. Or type “Control Panel” on the Start screen and select Control Panel in the search results.
3. In Control Panel, locate and double-click “Mail”.
4. Click “Show Profiles”.
5. Select your Outlook profile, click “Properties” and then click “Email Accounts”.
7. In the “Change Account” dialog box, click “More Settings”.
8. In the “Microsoft Exchange” dialog box, go to the “Security” tab.
9. In the “Logon network security” list, select “Anonymous Authentication”, then click OK.
10. Click “Next”, then “Finish”, and “Close” in the “Account Settings” dialog box.
11. Click “Close” in the “Mail Setup” dialog box, then click OK to close the Mail Control Panel.
Additional Information
To find and view the registry setting for anonymous authentication in the Outlook profile, follow these steps.
Important! Modifying the Outlook profile using the “Profiles” registry path is not supported and can cause the Outlook profile to be in an unsupported state. Follow all instructions in this section carefully. Making incorrect changes to the registry can lead to serious problems. Before making any changes, back up the registry for restoration in case of any issues.
1. Open the Registry Editor.
– In Windows 10, Windows 8.1, or Windows 8, press the Windows logo key + R to open the Run dialog box, type regedit.exe, and then click OK.
– In Windows 7, click Start, type regedit in the “Start Search” box, and press Enter. If you are prompted for an administrator password or confirmation, type the password or click “Allow”.
2. Locate the registry path appropriate for your version of Outlook:
– Outlook 2013: HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Profiles
– Outlook 2010 and 2007: HKEY_CURRENT_USER\Software\
Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles
3. In this subtree, find and expand the name of your Outlook profile.
Note: In my example, I navigate to the Office\16.0 folder, but follow the path in step 2.
4. Under the profile, locate and expand the registry subkey 9375CFF0413111d3B88A00104B2A6676.
5. Under the 9375CFF0413111d3B88A00104B2A6676 subkey, you will see a registry subkey for each account in your profile. Select the first subfolder (00000001), then check the binary data of the “Account Name” value by double-clicking the value. Repeat this process until you find the account name value that includes your SMTP address. For example, the account name value might indicate guidopica@contoso.com under the subkey \00000003.
In my example, it is the subkey \00000002
6. Under the \0000000x subkey, find the binary value “Service UID“. It represents a GUID (for example, c3 d1 9a 7b 80 1b c4 4a 96 0a e5 b6 3b f9 7c 7e).
7. Locate the subfolder in your profile that corresponds to the GUID value found in step 6 (for example, \c3d19a7b801bc44a960ae5b63bf97c7e).
8. Under the subkey found in step 7, check the binary value 01023d0dd. This value determines whether Outlook uses anonymous authentication.
– Binary: 00036619
– Data: 01 f0 00 80 == Anonymous Authentication
Any other value represents an authentication method other than anonymous.
If you have a different value, change it to 01 f0 00 80, which corresponds to the “Anonymous Authentication” setting.
