If you are being prompted for your password in Outlook try the steps below, one at a time to resolve the issue.

  1. Can the user log into Webmail?  If yes, have them restart Outlook.

  2. Clear your cached passwords (Note: you may need Admin rights to do this)
    1. Exit Outlook.
    2. Choose Start > Settings > Accounts > Email & app accounts
    3. Select the Outlook account then click Manage > Delete account
    4. Exit and reboot your computer. 

  3. Rename the Outlook .ost file (if get error about "cannot open set of folders")
    • Close Outlook.
    • Start Run by pressing Windows Key + R.
    • In the Run window, copy and paste this path in the Open box  "%LOCALAPPDATA%\Microsoft\Outlook\"
    • Click OK
    • Find the .ost file related to your account and rename it
      (you may need to Show Hidden Files and Show Extensions to see the file)
    • Restart the computer
    • Restart Outlook
  4. Verify that prompt for Credentials isn’t checked in profile:
    • Start Outlook
    • Choose  File | Account Settings | Account Settings
    • Select your Exchange account  
    • If prompted, in the Password: text box, type your password
    • Click the Change button 
    • Click the More Settings button
    • Select the Security tab
    • Deselect the "Always prompt for logon credentials" check box
    • Click OK,
    • OK
    • Choose Close
    • Restart Outlook.
  5. Creating a New Profile 
    • Exit Outlook
    • Start Run by pressing Windows Key + R.
    • In the Run window, type "Control Panel"
    • Click OK
    • In the Control Panel double click Mail [may say Mail 32-bit or  Mail (Microsoft Outlook 2016)]
    • Click Show Profiles
    • Click Add
    • Type the name of the profile e.g. your name and click OK
    • ​Enter your name and email if it doesn’t default in automatically
    • Click Next – it should auto configure
    • Click Finish
    • Back in the Mail window – Select your new profile in the "Always use this profile" dialog box and click Ok. 
    • Open Outlook and then re-open any .pst or archive files you have.