do you use a smart host ,
try this?
To resolve this issue, use the following steps:
Start the Internet Services Manager, and then right-click (click with the right mouse button) the Web site.
Click Properties, and then click the Server Extensions tab.
Under Options, click Settings.
In the E-mail Settings dialog box, specify how e-mail messages are to be sent:
In the Web server's mail address box, type the e-mail address that you want to appear in the From line of e-mail messages sent by certain components in FrontPage, such as results forms.
NOTE: Be sure to use a valid e-mail address (do not use an IP address) that will not be filtered by your SMTP server. Many SMTP servers only allow e-mail from certain domains. Verify that the e-mail address that you use is included on the list of domains that the SMTP server will accept.
In the Contact address box, type the e-mail address that users should write to if they have problems. The address you type will appear on error messages that are displayed for some problems encountered by users of FrontPage.
In the SMTP Mail server box, type the name or IP address of the SMTP host that will route messages to or from the Web.
In the Mail encoding box, select the mail-encoding scheme that you want to use for your e-mail messages. The default is 8-bit encoding, which is the most commonly used scheme. You can change from one encoding scheme to another if you know that an e-mail recipient uses a different encoding scheme and cannot interpret your messages.
In the Character set box, select the name of the set of characters that you want to use in e-mail messages. Each character set is the alphabet of a language.
Click OK to close the E-mail Settings dialog box, and then click OK to close the Web site Properties dialog box.