OL98: (CW) ErrMsg: Unknown Recipient

In Microsoft Outlook 98, after replying to a mail message you receive an "Undeliverable" message from the system administrator. The message text is: Followed by an X500 format address, and "Unknown Recipient". For example:

To resolve this problem change the order in which addresses are processed on the Delivery tab of your mail profile properties.

If you have both Microsoft Exchange server and Internet mail transport providers in a single profile, AND the Exchange server also sends and receives mail via the Internet, the Microsoft Exchange server should come first in the profile. That gives the server a chance to modify the recipients on the outgoing SMTP message to replace the Microsoft Exchange Global Address List addresses with appropriate SMTP addresses. The Internet mail MAPI transport can not perform this translation.

To change the order in which addresses are checked, follow these steps:

1. Click Start, point to Settings and then click Control Panel.
2. Double click Mail and Fax (Mail, if Fax services are not installed).
3. On the Delivery tab, click to select Microsoft Exchange Transport.
4. Use the arrows to the right of the box to move the Microsoft Exchange Transport to the top of the list. Click OK, and then close the Control Panel window.
5. If Outlook was running, quit and then restart Outlook.