Outlook keeps asking for Logon Credentials

To the most common solutions for this problem are:

Check the Mailbox Security Settings

Go to 'Control Panel'
Go to 'Mail' or 'E-mail'
Go to 'E-mail accounts'
Go to the properties of the email account
Go to tab 'Security'
Is checkbox 'Always prompt for logon credentials' disabled?

Remove the mailbox credential in Credential Manager

Go to 'Control Panel'
Go to 'Credential Manager'
Click on 'Windows Credentials'
Find the mailbox credentials
In the case you can find this specific mailbox credentials, then you can remove it.

Start with new Outlook profile

Create a new Outlook profile
Go to 'Control Panel'
Go to 'Mail' or 'E-mail'
Go to 'Show Profiles'
Create new profile, etc.


Reboot computer and try again