E-mail to external recipients with the same e-mail domain causes NDR messages when using the POP3 Connector

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Article ID: 300681 - View products that this article applies to.
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SYMPTOMS

If you are using the POP3 Connector on a Microsoft Small Business Server 2000 or on a Microsoft Windows Small Business Server 2003-based computer, users on the local network may receive errors when they try to send mail to external recipients that use the same e-mail domain name. For example, if a user on the local network with the e-mail address LocalUser@Example.com sends mail to an external recipient with the e-mail address ExternalRecipient@Example.com, Microsoft Exchange 2000 Server or Microsoft Exchange 2003 Server returns a Non Delivery Report (NDR) message with details that are similar to the following:
Your message did not reach some or all of the intended recipients.

The e-mail account does not exist at the organization this message was sent to. Check the e-mail address, or contact the recipient directly to find out the correct address.
<sbs.domain name.com #5.1.1>
However, local users can send mail to all other local users and external recipients.

CAUSE

This behavior occurs when Exchange is configured to be responsible for the e-mail domain that the external POP3 mail server is hosting. When Exchange is responsible for an e-mail domain, it always tries to deliver mail that is addressed to that domain to a local recipient. If a local recipient with that e-mail address does not exist, Exchange generates the NDR message that is described in the "Symptoms" section.

WORKAROUND

To work around this behavior, use either of the following methods.

Method 1

Configure the SMTP virtual server in Exchange to send mail with unresolved recipients to the Internet service provider's (ISP's) mail server. To do this, follow these steps:
  1. Click Start, point to Programs or to All Programs, point to Microsoft Exchange, and then click System Manager.
  2. Expand Servers, expand Servername, expand Protocols, and then expand SMTP.

    Note If Exchange System Manager is configured to display the administrative groups, you must expand Administrative Groups before you expand Servers. Then expand the administrative group that contains the mail server.
  3. Right-click the SMTP virtual server, and then click Properties.
  4. Click the Messages tab, type the name or the IP address of the ISP's mail server under Forward all mail with unresolved recipients to host, and then click OK.

    The SMTP mail server that you specify must be the ISP mail server that receives messages for the POP3 accounts. This may be different from the POP3 server that you connect to when you download messages from the ISP.
  5. Right-click the SMTP virtual server, and then click Stop.
  6. Right-click the SMTP virtual server, and then click Start.

    Note In this case, any e-mail that local users send to recipients that do not exist on your server will be forwarded to the ISP's mail server.

Method 2

Configure the Default Policy in the Exchange recipient policy to use the local e-mail domain as the primary address, and then add an additional recipient policy to apply the POP3 e-mail domain to the local user accounts. This way, the e-mail domain for the local users will match the e-mail domain that the POP3 mail server is hosting, but Exchange will not be the responsible mail server for this e-mail domain.

Be aware that the user accounts must be configured to be updated by recipient policies. This option is available under the properties for each user on the Email-Addresses tab.

To configure the recipient policies in Exchange, follow these steps:
  1. Click Start, point to Programs or to All Programs, point to Microsoft Exchange, and then click System Manager.
  2. Expand Recipients, and then click Recipient Policies in the left pane. In the right pane, the Default Policy is listed.
  3. Double-click Default Policy, and then click the E-Mail Addresses tab.
  4. By default, an SMTP e-mail address that matches your internal domain name appears in the list of addresses. For example, if your internal domain name is mycompany.local, the address @mycompany.local will appear in the list. If the internal domain address is not listed, follow these steps to add it:
    1. Click New.
    2. Click to select SMTP Address, and then click OK.
    3. In the Address box, type the internal domain address, and then click OK. For example, type @mycompany.local.
  5. Click to select the internal domain address, and then click Set as Primary.
  6. Click to select the POP3 domain address, and then click Edit.
  7. Clear the box that says This Exchange Organization is responsible for all mail delivery to this address, and then click OK.
  8. Click OK to apply the changes.
  9. Click Yes or OK two times to update all corresponding recipient e-mail addresses.
  10. Right-click Recipient Policies in the left pane, point to New, and then click Recipient Policy.

    Note If you have Exchange Server 2000 Service Pack 1 (SP1) or later, a dialog box appears that prompts you to select the type of recipient policy that you want to create. In this case, click to select the E-Mail Addresses check box, and then click OK.
  11. Type a name for the recipient policy, and then click Modify.
  12. In the Find Exchange Recipients dialog box, click to select Users with Exchange mailbox, and clear all the other check boxes.
  13. Click OK, and then click OK on the warning message that you receive.
  14. Click the E-Mail Addresses tab.
  15. Click to select the POP3 domain address, and then click Set as Primary.
  16. Click OK to apply the changes.
  17. Click Yes or OK two times to update all corresponding recipient e-mail addresses.
Note Every time that you run the Internet Connection Wizard or the Configure E-mail and Internet Connection Wizard and set it to modify the Exchange settings, the wizard will set the e-mail domain address that you enter in the wizard as the primary address on each recipient policy. After the wizard is completed, you must repeat the steps that are mentioned in this article to modify the recipient policy.

STATUS

This behavior is by design.

Properties

Article ID: 300681 - Last Review: December 3, 2007 - Revision: 3.3
APPLIES TO
  • Microsoft Small Business Server 2000 Standard Edition
  • Microsoft Windows Small Business Server 2003 Premium Edition
  • Microsoft Windows Small Business Server 2003 Standard Edition
Keywords: 
kberrmsg kbenv kbnetwork kbprb KB300681

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