Why does Outlook keep prompting for password?

Applies to Exchange 2010 and Exchange 2016 hosted accounts. You might be wondering why does Outlook keep prompting for a password? Here are a few common problems below.

• Outlook is configured to prompt you for credentials
• Incorrect password cached in credential storage
• Required Authentication Settings for outgoing server and incoming server
• Outlook Anywhere is not configured to use NTLM Authentication
• Corrupt Outlook profile
• Slow or unstable network connection
• Antivirus programs
• Shared calendars

Outlook is configured to prompt you for credentials

If you are using an Exchange account, there is a setting in your Outlook profile to always prompt for logon credentials. To find the setting, please follow:

1. In Outlook 213, go to File tab > Info > Account Settings > Account Settings…

2. Highlight your Exchange account and click Change button.

3. Click on More Settings button.

4. Select the Security tab.

5. Under the User Identification, make sure the “Always prompt for logon credentials” option is not selected.

If you are using other types of email, please make sure you have ticked the option “Remember password”.

Incorrect credential cached in Credential Manager

Your Windows system stores user credentials on your computer. If the cached credentials are incorrect, you will be prompted for password. This issue usually happens after the password for your domain user account is changed. Before your password changed, you saved your credentials. The stored credentials are not overwritten when Outlook triggers the authentication prompt even if you enable the Remember my credentials option.

To fix this issue, you need to remove the corrupted credentials, follow these steps:

1. Click Start, click Control Panel, and then click Credential Manager.

Note If View by is set to Category, click User Accounts first, and then click Credential Manager.

2. Locate  the set of credentials that has Outlook in the name.

3. Click the name to expand the set of credentials, and then click Remove from Vault.

Repeat step 3 for any additional sets of credentials that have the word Outlook in the name.

Required Authentication Settings for outgoing server and incoming server

Different email provider may need different authentication settings. Please make sure you have set the server settings correctly. You can contact your email provider to gather the information.

In general, we select the “My outgoing server (SMTP) requires authentication” option and the first bullet “Use same settings as my incoming mail server”.

In addition, click on the Advanced tab and check if you have enter the correct Server Port Number and select the correct encrypt type. Below is a screenshot for an IMAP account:

Outlook Anywhere is not configured to use NTLM Authentication

The Outlook Anywhere feature allows you to access your Exchange account remotely from the Internet when you are working outside your organization’s firewall.

When using Outlook Anywhere to connect to your Exchange server, we need to choose the authentication method among Basic Authentication, NTLM Authentication and Negotiate Authentication. The difference among them is the way that the passwords are sent when connecting to the server. With Basic Authentication, the password is sent in clear text. Using NTLM Authenticationcan significantly reduce the number of password prompts.

To check the authentication setting, please go to File > Account Settings > Account Settings, select the Exchange account, and then click Change. In the Change Account wizard, click More Settings, and then click the Connection tab. Click the Exchange Proxy Settings button and now, you can see the settings under Proxy authentication settings. Try to change the authentication to NTLM Authentication and then check the issue again.

Slow or unstable network connection

If your network connection is slow or unstable, Outlook may lose connection to the mail server. When Outlook try to reconnect, it will prompt for the credentials. To verify this, please switch to a stable network environment and then check if this issue persists.

Corrupt Outlook Profile

Corrupt profile may cause Outlook to no longer remember your password. Please try to create a new mail profile in Control Panel and reconfigure your email account in the new profile to fix the issue. To create a new mail profile, you can refer:

http://support.microsoft.com/kb/829918

Antivirus software

Antivirus software usually integrates into your Outlook and it may cause some conflicts. Try to temporarily turn off your antivirus software to check if the issue will be gone.

Shared Calendar

Shared calendars can impact the user credentials, this issue may also occur if you have shared calendars opened in Outlook. You can try to unselect the shared calendar to check the result. It’s recommended to not open the shared calendar unless you want to view them.

The referencing link is: https://social.technet.microsoft.com/Forums/en-US/bcd2d9c2-1a1b-4446-bf32-69fee8cdf11b/why-does-outlook-keep-prompting-for-password?forum=outlook