KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q217388: XCON: IMAP4 Referral Support

Article: Q217388
Product(s): Microsoft Exchange
Version(s): winnt:5.5
Operating System(s): 
Keyword(s): 
Last Modified: 21-MAR-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Exchange Server, version 5.5 
-------------------------------------------------------------------------------

SUMMARY
=======

This article explains IMAP referral as it relates to Microsoft's current IMAP
clients and Exchange Server, and future plans for these products.

IMAP referral is the process where, initially, an IMAP client issues a logon
command to an IMAP server that is not the IMAP client's home server. The IMAP
server passes the client's logon command to another IMAP server that can
authenticate the client. IMAP referrals happen behind the scenes and are
transparent to the user.

Exchange Server version 5.5 supports referrals, but not completely. You will be
referred to the correct server, but you will not be able to retrieve mail. For
automatic referrals to work properly, Exchange Server computers that will
participate in this referral "scheme" must be configured to do directory
replication amongst themselves. After the Exchange Server computers have
replicated successfully, all IMAP logon requests will be "referred" to the
appropriate IMAP server by means of a directory lookup.

The long-term plan is to have Exchange Server be a "front-end" for the referral
for non-supporting clients, meaning that a single properly configured Exchange
Server computer would transparently handle the referral for the non-referral
IMAP clients. At this time, front-end referral functionality is not available in
Exchange Server 5.5 and earlier versions, but will be included in the next
release of Exchange Server.

Unfortunately, Post Office Protocol 3 (POP3) does not have the ability to do
referral request and responses. Also, Outlook Express and other Microsoft IMAP
clients do not support referrals and are not expected to support referrals in
the future release.

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

Below are some instructions on the protocol commands that you can use in a
telnet session to see if the IMAP server supports referrals:

1. In Windows NT 4.0, click Start, and then click Run.

2. In the Open text box, type "telnet <SECOND> 143" (without the quotation
  marks), and press ENTER.

  NOTE: <SECOND> represents the name of the second server; do not include
  the angle brackets (<>).

  You should see a new window appear with a banner that looks similar to the
  following:

  * OK Microsoft Exchange IMAP4rev1 server version 5.5.1960.6 (reedlm4.com)
  ready

3. On the Terminal menu, click Preferences. Make sure the Local Echo check box
  is enabled, and then click OK.

4. At the prompt, type "? login <NTdomain>/<domain
  userID>/<Exchange Alias> <password>" (without the quotation
  marks), and press ENTER. For example, if your Windows NT domain is DOMname,
  your domain user is UserN, your Exchange alias is AliasN, and your password
  is PASSword, then you would type:

  ? login DOMname/UserN/AliasN PASSword

NOTE: The the direction of the slashes is very important; the question mark,
followed by a space at the beginning of the line is also important. Backspacing
is not allowed; if you make a mistake, you have to press ENTER, and start a new
line.

5. The response you will get will be something like:

  ? OK [REFERRAL imap://redmond%2Freedl%2Fimapf;AUTH=*@reedlm1.reedlm1.com]
  LOGIN completed

6. At this point, you are logged onto the other IMAP server. When you issue any
  commands, such as ? Select Inbox, to enter into your Inbox, you may receive
  the following message:

  NO There is no replica for that mailbox on this server.

7. You can log out of the telnet connection by typing "? logout" (without the
  quotation marks) at the command prompt, and pressing ENTER.

Additional query words:

======================================================================
Keywords          :  
Technology        : kbExchangeSearch kbExchange550 kbZNotKeyword2
Version           : winnt:5.5
Issue type        : kbhowto

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.