XFOR: Disabling 8-BIT MIME Support on the Windows NT Option Pack SMTP Service

ID: Q198415

The information in this article applies to:

SUMMARY

Exchange Server administrators may notice the following error message:

500 Host does not support 8bitmime
This might be a result of a mail host attempting to send 8-bit MIME messages to the Exchange Server computer. The Windows NT Option Pack comes with an SMTP service that can be used as a relay host between the Internet and Exchange Server. By default, this SMTP service advertises and allows 8- bit MIME messages to be relayed. This article describes how to prevent outside mail hosts from sending in 8-bit MIME messages by disabling the advertisement of 8BITMIME.


MORE INFORMATION

To make the Windows NT 4.0 SMTP Service stop advertising 8BITMIME, you need to alter the metabase key that tells it to advertise 8BITMIME. Use the Mdutil.exe utility that is included on the Windows NT Option Pack CD.

NOTE: Mdutil.exe is not installed with the Option Pack by default.

To turn the 8BITMIME advertising off, set the advertisement of 8BITMIME to 0 by typing the following command at a command prompt:

mdutil.exe set -path:smtpsvc -prop:36865 -utype:UT_SERVER -dtype:DWORD - attrib:INHERIT -value:0
NOTE: The above command is shown on two lines for convenience, but it should be typed as one continuous command. You may need to stop and restart the SMTPSVC for this option to take effect. To verify that disabling or enabling 8BITMIME has taken effect, you can do the following:
  1. From a command prompt, type the following command:
    telnet localhost 25
    After it connects, you should see a banner response with "ESMTP spoken here."


  2. On the Terminal menu, click Preferences, and verify that the Local Echo check box is selected, and press OK.


  3. In the Telnet window type the following command:
    EHLO yourdomain.com
    Where yourdomain.com is your e-mail domain, and press ENTER. You should then get a response of 250- and various options. If you disabled the 8BITMIME, it should no longer be listed.


  4. Type Quit in the Telnet window to close the session, then close the Telnet window.


The response should be: 

   36865                         : [IS]    (DWORD)  0x0={0}
The number at the beginning of the returned line, 36865, is the property ID number for 8BITMIME. The hexadecimal value (0x0)={0} means that 8BITMIME advertising is turned off.

To turn MIME broadcasting back on, execute the above command after replacing -value:0 with -value:1. This sets the parameter value to 1, which turns MIME broadcasting on. 


Keywords          : 
Version           : winnt:4.0,5.0,5.5
Platform          : winnt 
Issue type        : kbhowto

Last Reviewed: May 12, 1999