Q221384: XFOR: Pickup Directory Files w/Single Period Aren’t Padded Right

Article: Q221384
Product(s): Microsoft Exchange
Version(s): winnt:2.0,4.0,5.5
Operating System(s): 
Keyword(s): exc55
Last Modified: 09-OCT-1999

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The information in this article applies to:

- Microsoft Exchange Server, version 5.5 
- Microsoft Internet Information Server 4.0 
- Microsoft Commercial Internet System version 2.0 
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SYMPTOMS
========

When you use Internet Information Service SMTP service to create SMTP mail by
copying files to or creating files in the Pickup subdirectory or when you use
the Exchange Server Internet Mail Service to create SMTP mail in the Mailroot
directory, mail may prematurely end for the recipient.

Each line after the end causes the remote system to interpret the text as a
command and generate a "500 Command Unrecognized" error message.

CAUSE
=====

The SMTP service does not explicitly ascertain whether the processed files have
a single period on a line by itself in the message contents. Consequently, when
a file that contains a single period on a line by itself is copied into the
Pickup directory, the period is interpreted as the end of the message, and the
message is truncated at the period. Each line after the period causes an error,
which produces a "500 Command Unrecognized" error message on the remote system.
Unless you run a network trace, the only indication of a problem is that the
messages are truncated.

WORKAROUND
==========

When you copy files to the Pickup directory, ensure any single periods are
escaped or padded with another period (that is, when you want a period on a line
by itself, type two periods).


STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products that are
listed at the beginning of this article.

MORE INFORMATION
================

To Reproduce the Problem:

1. Stop the SMTP service:

  "net stop smtpsvc" (without the quotation marks)

2. In Notepad, create the following message and save it in a file called
  Message.txt in the Pickup directory:

  x-sender: Sender
  x-receiver: user1@valid.but.unreachable.host
  Subject: Testing.

  Testing

  .

  Testing
  <EOF>

3. Restart the SMTP service.

  "net start smtpsvc" (without the quotation marks)

NOTE: The remote user will not see the second "Testing" text.
RFC 821, Section 4.5.2 states:

4.5.2.  TRANSPARENCY

        Without some provision for data transparency the character
        sequence "<CRLF>.<CRLF>" ends the mail text and cannot be sent
        by the user.  In general, users are not aware of such
        "forbidden" sequences.  To allow all user composed text to be
        transmitted transparently the following procedures are used.

           1. Before sending a line of mail text the sender-SMTP checks
           the first character of the line.  If it is a period, one
           additional period is inserted at the beginning of the line.

           2. When a line of mail text is received by the receiver-SMTP
           it checks the line.  If the line is composed of a single
           period it is the end of mail.  If the first character is a
           period and there are other characters on the line, the first
           character is deleted.

What occurs is that remote systems interpret the "<CRLF>.<CRLF>"
sequence as ending the message.

Note that this problem also occurs with the Pickup subdirectory of the Imcdata
directory in Exchange Server 5.5.

Additional query words:

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Keywords          : exc55 
Technology        : kbiisSearch kbAudDeveloper kbExchangeSearch kbExchange550 kbiis400 kbZNotKeyword2 kbMCISSearch kbMCIS200
Version           : winnt:2.0,4.0,5.5
Issue type        : kbbug
Solution Type     : kbnofix

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