After the Microsoft Mail Gateway to SMTP starts and initializes, it checks
for outgoing mail from the SMTP outgoing queue. If it detects outgoing
mail, it opens a session with the smarthost and begins to process the
If the gateway comes to a message in the queue that it cannot process,
this error message may occur:
ERROR translating message to SMTP: protocol error
This error can result from a damaged message in the SMTP gateway queue.
When there is a damaged message in the queue, the gateway stops processing
the outgoing messages and switches to the idle state waiting for TCP/IP
connections. It then repeats the same process during its next scheduled
connection attempt time.
The problem message in the SMTP queue should either be deleted or returned
to the sender. You may want to first rename the temporary files used by the
SMTP gateway that are found in the MAILDATA\SMTP directory. Any file with
extension .API in the SMTP directory should be changed to an extension of
.OLD with the following command:
ren *.api *.old
Deleting or returning of messages is done from within the ADMIN.EXE
- Start ADMIN.EXE with an account that has Admin privileges.
- From the Admin menu, choose Queue.
- In the dialog box, type SMTP and press the ENTER key.
- Return the problem message (probably the first or last message in the
- The user who sent the message needs to resend the returned message or be
notified that it was deleted.
NOTE: If there is a file called FROM_NC.API or OUTBAD.API in the SMTP
directory of the Mail Postoffice, you can view this file and decipher who
the sender of the problem message is. The sender's name is preceded with
a FROM: and contains the full 10/10/10 Microsoft Mail address. Once you
have this information, you follow the steps above to remove the message
from the SMTP outgoing queue. It is suggested to use Debug since many
MS-DOS editors show the file as one big line of text.
Assume there is a file stranded in the M:\MAILDATA\SMTP directory called
OUTBAD.API. Use the following steps to find the sender of the problem
- Type the following:
- At the hyphen (-) prompt, type the letter D and press the ENTER key.
- A mix of HEX values and ASCII text is displayed on the screen,
repeatedly press D, ENTER until the word FROM: shows up in the ASCII
- Note the information following the FROM: because this is the sender of
the problem message.
NOTE: There may be multiple messages in the .API file, where each one
has its own FROM: information. If the old .API files are renamed
prior to the startup of the gateway as mentioned above, a new file
containing only the problem message should be created.
- Use this name when following the steps above to return or delete the
message out of the SMTP queue.
NOTE: The "protocol error" message can be a vague error message and may
refer to a number of other issues. The resolution in this article has
been proven to work in many situations where this error occurred.
Article ID: 98159 - Last Review: October 30, 2006 - Revision: 1.1
- Microsoft Mail Gateway to SMTP 3.0
Retired KB Content Disclaimer
This article was written about products for which Microsoft no longer offers support. Therefore, this article is offered "as is" and will no longer be updated.