Setting up basic authentication for one user in Exchange (On-Prem Server)

How to setup basic authentication for one user in Exchange Server 2019. Here's a step-by-step guide:

Step 1: Ensure Basic Authentication is Enabled on the Server

By default, basic authentication might be disabled on the Exchange server due to security concerns. Verify and enable it for the required services if needed.

1.1. Check the status of Basic Authentication

You can check whether basic authentication is enabled for specific services (like IMAP, POP3, or SMTP) using the following commands in the Exchange Management Shell (EMS):

Powershell: Get-ClientAccessService | Select-Object Name, IMAPAuthMechanism, POP3AuthMechanism, SmtpAuth

1.2. Enable Basic Authentication for the required service

If basic authentication is not enabled, you can enable it by running:

For IMAP -> powershell: Set-ImapSettings -LoginType PlainTextLogin

For POP3 -> powershell: Set-PopSettings -LoginType PlainTextLogin

For SMTP -> powershell: Set-SmtpReceiveConnector -Identity "ConnectorName" -AuthMechanism "BasicAuth"

Step 2: Configure Authentication Settings for the User

2.1. Using Exchange Admin Center (EAC)

1. Login to EAC: Open the Exchange Admin Center in your web browser.

2. Navigate to Recipients:

   • In the left-hand navigation pane, click on "Recipients" and then click on "Mailboxes."

3. Select the User:

   • Find the user you want to configure and double-click on the user’s name to open their properties.

4. Authentication Settings:

   • In the user’s properties, go to the "Mailbox Features" tab.
   • Scroll down to the "Email Connectivity" section (this is where you can manage POP and IMAP settings).
   • Make sure that the appropriate protocols (IMAP, POP, SMTP) are enabled.
   • To enforce basic authentication, you may need to adjust the settings depending on the protocol being used (this may require command-line adjustments as detailed in Step 1).

5. Save Changes:

   • After adjusting the settings, click "Save" to apply the changes.

2.2. Using Exchange Management Shell (EMS)

1. Enable/Disable POP, IMAP, or SMTP for the User:

   • Enable or disable specific protocols for the user by running:

   For POP3 -> powershell: Set-CASMailbox -Identity "username" -PopEnabled $true

   For IMAP -> powershell: Set-CASMailbox -Identity "username" -ImapEnabled $true

   For SMTP -> powershell: Set-CASMailbox -Identity "username" -SmtpClientAuthenticationDisabled $false

2. Verify the Configuration:

   • To verify if the settings have been applied correctly:
   powershell: Get-CASMailbox -Identity "username" | Format-List PopEnabled,ImapEnabled,SmtpClientAuthenticationDisabled


Step 3: Testing the Configuration

After configuring the user’s mailbox for basic authentication:

1. Test Connectivity: You can test the user's connection via IMAP, POP3, or SMTP using a mail client (like Outlook or Thunderbird) by configuring it with the user’s credentials. Ensure that basic authentication is selected as the login method.

2. Troubleshoot If Necessary: If there are issues with authentication, check the Exchange logs or use tools like Telnet to verify that the services are responding correctly.

Step 4: Security Considerations

Basic authentication sends credentials in an unencrypted format, which could be intercepted. It's recommended to:

1. Use SSL/TLS: Ensure that the connection to the Exchange server is secured using SSL/TLS. This can be enforced on IMAP, POP3, and SMTP settings.
2. Monitor and Audit: Regularly monitor and audit the use of basic authentication, and consider switching to modern authentication methods (OAuth, for instance) as soon as possible.

This guide provides a basic overview of enabling and configuring basic authentication for a single user in Exchange 2019. Be sure to adapt and secure your environment according to your organization's policies and security requirements.