Outlook 2007 prompting users for Credentials

OUTLOOK 2007 KEEPS PROMPTING USERS FOR PASSWORD

After migration from Exchange 2003 to Exchange 2010 outlook 2007 keeps prompting users for password:

Symptoms

After you migrate Exchange 2003 to Exchange 2010, some outlook client users keep getting prompted to enter their credentials again.

Cause

The problem might be related to the authentication method used on Outlook Anywhere. (Basic Authentication).

The recommended approach is to use NTLM authentication which keeps credentials cached.

Resolution:

Changing the authentication method of Outlook anywhere to NTLM will resolve the issue.

Ref:

https://support.microsoft.com/en-au/help/956531/outlook-2007-prompts-you-repeatedly-for-a-password-under-certain-netwo