The POP3 Connector May Not Deliver Mail to Users

When the Connector for POP3 Mailboxes component downloads e-mail messages from an Internet service provider (ISP), all of the available messages are downloaded from the individual mailboxes or the global mailbox as expected. However, any of the following symptoms may occur:

• Some of the messages that are downloaded by the POP3 connector may not be delivered to the recipients.
• The originators of these messages may not receive non-delivery reports from the Microsoft Exchange 2000 Server-based computer as they typically do if their messages do not reach the intended recipients.
• The Exchange 2000 Server-based computer may not log any errors in the Small Business Server (SBS) 2000 event logs.
• The POP3 service may not log any errors in the Application event log with default diagnostics logging set.
• The downloaded messages disappear.

With diagnostic logging set to the maximum level for the POP3 Connector Delivery service, the following events are logged after e-mail messages are downloaded:

This behavior occurs if there is no recipient policy for the expected domain in the Exchange 2000 organization.

Add a recipient policy for the expected domain. To do so:

1. In Exchange System Manager, expand the Recipients object, and then expand the Recipient Policies object.
2. In the right pane, right-click Default Policy, and then click Properties.
3. Click the E-Mail Addresses (Policy) tab.
4. Click New, click SMTP Address, and then click OK to add a new SMTP address.
5. In the Address box, type @expecteddomain.com, where expecteddomain is the domain to which the sender is trying to send mail. Click Apply, and then click OK.
6. In the Default Policy Properties dialog box, click the E-Mail Addresses (Policy) tab, and then click to select the check box next to the SMTP address that you just created.
7. Click Apply. Click Yes when you receive the following prompt:
   The e-mail addresses of type(s) [smtp] have been modified. Do you want to update all corresponding recipient e-mail addresses to match these new address(es)?
   If you want to make the new SMTP address the default reply-to address for all of the users in your Exchange 2000 organization, click the new address, click Set as Primary, click Apply, and then click OK.
   
   If you want to update the Default Policy immediately, right-click Default Policy, and then click Apply this policy now.

This behavior is by design.

For global mailboxes, the POP3 connector downloads the e-mail messages from the global mailbox on the POP3 server. The POP3 connector scans the "To" and "Cc" header fields in the message to determine the local recipients and then adds the recipient's address or addresses to the envelope. The message is then submitted to the SMTP service on the local Exchange 2000 Server-based computer, which delivers the mail to the correct mailbox.

For individual user mailboxes, the POP3 connector downloads the e-mail messages from the POP3 server. The POP3 connector then modifies the recipient's address for the envelope based on the mapping from the POP3 Connector mailbox account to the Exchange recipient account. This mapping is maintained in the POP3 connector properties. The envelope recipient's address is changed to the Exchange recipient's primary SMTP address so that the e-mail message is designated for a user's e-mail account on the local Exchange 2000 Server-based computer instead of for the user's POP3 account. The message is then submitted to the SMTP service on the local Exchange 2000 Server-based computer, which delivers the mail to the correct mailbox.

The Exchange recipient policy is used to generate the proxy addresses for Exchange recipients. By default, this includes SMTP and X.400. You can use the Exchange recipient policy to set the global primary SMTP address for all recipients on the server if more than one SMTP domain is included in the policy. By default, if only one SMTP address is included in the recipient policy, it becomes the primary SMTP address. An individual recipient may have a primary SMTP address that is different from the global primary SMTP address that is set in the Exchange Server recipient policy. This can occur if the recipient's account in the Microsoft Windows 2000 Active Directory Users and Computers console is specifically set to disable automatic updates of the recipient's e-mail addresses based on the recipient policy. The Exchange 2000 Server recipient policy is also used to define the e-mail domains for which the Exchange server will accept and deliver e-mail messages.

When the POP3 connector submits messages to the SMTP service, the SMTP service compares the e-mail domain of the envelope's recipient address to the e-mail domains that are defined in the Exchange recipient policy. If there is a match, the SMTP service accepts and processes the message. If no match is found, the SMTP service rejects the message if the service does not permit relaying. If the SMTP service permits relaying, it accepts the message and processes the message as an outbound e-mail message that is destined for an e-mail server on the Internet.