We're running Outlook 2013 with exchange. Users have Sharepoint 2007 calendars linked to their Outlook accounts. Recently, Outlook has started prompting users for their sharepoint credentials when Outlook performs a send/receive for the first time after being opened. Even after the 'remember credentials' box is selected, Outlook continues to prompt for credentials upon the first send/receive. Here are the steps I've tried so far to resolve this issue: 

Removed and re-added Sharepoint Calendar. 

Removed Outlook Profile and re-added

Removed sharepoint credentials from credentials manager and re-added credential under general credentials.(The credentials box was initially empty upon each prompt, but after this step the username and password was automatically filled. However, the credentials box still appeared)

Tried adding a password to the Calendar file itself under Account Settings > Data Files > Sharepoint list > Change Password. 

Added Sharepoint to list of trusted sites in IE and changed user authentication levels in custom levels to automatic login with current username and password. Also tried to add to intranet list.

Cleared IE settings and passwords. 

I've seen several people with similar issues but nothing quite the same, or the issue was resolved through the steps above. 

Thanks in advance for any help.

• Edited by jamestoto Monday, May 04, 2015 6:28 AM

Hi,

Do you have any third-party add-in installed? I've seen such issue caused by problematic add-ins. We can try opening Outlook in safe mode to verify if it is an add-in issue. Press Windows key + R to open the Run command, type outlook /safe and press Enter. If the problem would be gone in safe mode, please go to File > Options > Add-ins and disable suspicious add-ins to resolve the issue.

If above doesn't applies, please also try the following steps and check if it helps:

1. Open your Internet Explorer.

2. Click Tools > Internet Options > Security tab.

3. Select Local intranet, and then click Custom level button.

4. Scroll down to the bottom and select "Automatic logon with current user name and password" under Authentication section > Logon section.

5. Click OK. Click OK again.

6. Restart Outlook and then test the issue again.

Please let me know the result.

Thanks,

Steve Fan
TechNet Community Support