Understanding the POP3 Connector

Applies To: Windows SBS 2008

You can use the Windows SBS 2008 POP3 Connector to retrieve e-mail from external POP3 mailboxes and deliver it to the appropriate Exchange Server users. For example, you can retrieve e-mail from the POP3 mailbox for Chris@adatum.com (where adatum.com is the domain name of Chris' Internet service provider), and then deliver it to your Exchange e-mail mailbox for Chris@contoso.com.


When a user replies to a message that is received from an external POP3 mailbox, the reply is sent from your local Exchange Server. Windows SBS 2008 does not route the reply through the original POP3 e-mail server.

POP3 Connector features

You can use the POP3 Connector to do the following:

  • Retrieve e-mail from an external POP3 mailbox account and deliver it to an Exchange Server mailbox for a specified Windows SBS 2008 user.

    A POP3 mailbox is a mailbox account that is located on an external server. Use the POP3 Connector to designate the Windows SBS 2008 user account or distribution group to deliver e-mail that is sent to a specified POP3 mailbox account.

    When the POP3 Connector accesses a users POP3 mailbox, it downloads the messages, and then delivers the messages to the designated mailbox for the local user account or distribution group. For example, the POP3 Connector retrieves e-mail from the POP3 mailbox for Chris@adatum.com, and then delivers the e-mail to the Exchange Server mailbox for Chris@contoso.com.

  • Manage POP3 mailboxes by using the Windows Small Business Server POP3 Connector properties page.

    On the Accounts tab, you can add, edit, or remove POP3 mailboxes. On the Scheduling tab, you can define a schedule for retrieving POP3 e-mail, which enables you to retrieve POP3 e-mail immediately.

    For information about how to configure the POP3 Connector for your organization, see Configure the POP3 Connector.

    The POP3 Connector supports connecting to the POP3 server by using a Secure Sockets Layer (SSL) connection. If your POP3 server supports SSL, it is recommended that you configure the POP3 connector to connect by using SSL. Additionally, the POP3 Connector supports the following types of authentication to the POP3 server:

    • Basic.   In this type of authentication, the logon credentials for the POP3 account are sent as unencrypted clear text to the e-mail server for the POP3 mailbox.


Basic authentication offers the lowest level of authentication security. Because of this, you should not use Basic authentication if a POP3 account supports one of the other methods of authentication discussed here.

  - **Secure Password Authentication (SPA)**.  SPA uses encrypted authentication credentials to log on to the e-mail server for the POP3 mailbox each time the POP3 Connector downloads e-mail. Some ISPs require that you use SPA.  
  - **Authenticated Post Office Protocol (APOP)**.  APOP uses MD5 password encryption to provide enhanced security during message authentication.  

POP3 Connector requirements

  • Using the POP3 Connector requires that Exchange Server is installed and that the Exchange Server services are running.

  • Before you can configure the POP3 Connector, you must perform the Set up your Internet address task on the Windows SBS Console home page.

  • Domain Administrator permissions are required to manage the POP3 Connector.

  • Obtain the following information for each POP3 e-mail account:

    • The name of the POP3 e-mail server

    • The user name for the POP3 account

    • The password for the POP3 account

    • The port used by the ISP to transmit POP3 mail (usually port 110, or 995 for SSL connections)

    • The method of authentication that is supported or required for the POP3 account


You should always configure the most secure method that is supported by your server and the ISP.

How your server handles spam

The POP3 Connector uses the Simple Mail Transfer Protocol (SMTP) to submit e-mail messages to Exchange Server. Exchange then uses the antispam agent to scan these messages. If a message is determined to be spam, Exchange does not deliver the message to the user. Instead, the message is stored in a folder within the following folder on the server:

C:\Program Files\Windows Small Business Server\Data\badmail.

Maximum message size

The maximum message size that can be processed by SMTP is 10 MB. Because of this, the POP3 Connector does not attempt to retrieve messages that exceed 10 MB in size. If a POP3 mailbox contains a message larger than 10 MB, Windows SBS 2008 logs an event that advises you to download or delete the message manually, or increase the maximum message size that Exchange Server accepts.

Using the POP3 Connector

To access the Windows Small Business Server POP3 Connector properties

  1. Open the Windows SBS Console.

  2. On the navigation bar, click Network.

  3. Click the Connectivity tab.

    The list view displays information about your network connections.

  4. In the list view, click POP3 Connector.

  5. In the Tasks pane, click View POP3 Connector properties.

Viewing POP3 Connector error messages

The POP3 Connector records errors in the Windows SBS 2008 event log. You can use Event Viewer to browse these errors.

To view error messages for the POP3 Connector

  1. Click Start, type eventvwr, and then press ENTER.

  2. In the console tree, expand Applications and Service Logs.

  3. Expand Windows Small Business Server 2008, and then select Microsoft Windows Small Business Server/Operational.

    The details pane displays error and event messages for Windows SBS 2008 including error messages from the POP3 Connector.