Microsoft KB Archive/277986

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XFOR: Description of an Exchange 2000 SMTP Banner

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Q277986

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The information in this article applies to:


 * Microsoft Exchange 2000 Server

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SUMMARY
When a telnet session is initiated to a computer that is running Microsoft Exchange 2000 Server at port 25, a banner similar to the following is displayed:

"220 smtp01.northamerica.corp.microsoft.com Microsoft ESMTP MAIL Service, Version: 5.0.2195.1600 ready at Wed, 25 Oct 2000 13:29:34 -0500"

MORE INFORMATION
This banner originates from Request for Comments (RFC) 821 section 3.5. The banner can be broken into four separate elements:


 * Reply Code
 * Host
 * Software
 * Date and Time

Reply Code
The reply code in this example is 220.

Reply codes are described in sections 4.2 and 4.3 of RFC 821. A Simple Mail Transfer Protocol (SMTP) reply consists of a three-digit number (transmitted as three alphanumeric characters) followed by some text. The original objective for the reply code is to quickly output a computer-readable response. A formal discussion of reply code theory is outlined in RFC 821, Appendix E. The following related points are from Appendix E:


 * 2xy: The first value, 2, denotes &quot;Positive Completion reply.&quot;
 * x2y: The second value, 2, denotes &quot;Connections.&quot;
 * xy0: The last digit, 0, provides the option to give a finer gradation of meaning in each category.

Therefore, a value of 220 means that a connection has completed successfully.

Host
In this example, the host or computer name is smtp01.northamerica.corp.microsoft.com. Therefore, the Domain Name Service (DNS) domain name is northamerica.corp.microsoft.com, and the computer name is smtp01. This type of notation is referred to as a Fully Qualified Domain Name (FQDN) because it relates or qualifies the host as a member of a domain that is registered with root DNS servers.


 * Host: smtp01
 * Subdomains: northamerica and corp
 * Domain: microsoft
 * Root Domain: com

NOTE: In Active Directory and DNS, a node is any name that is a child to a domain. Therefore, in the preceding example, smtp01, northamerica, and corp are all considered nodes even though smtp01 is a computer and northamerica and corp are subdomains.

Software
The following SMTP service (software) is being used for the information in this article:

"Microsoft ESMTP MAIL Service, Version: 5.0.2195.1600" This version of the ESMTP Service is the version of the SMTP stack that was upgraded when Exchange 2000 was installed.

The default SMTP stack that is installed with Microsoft Windows 2000 is:

"Microsoft ESMTP MAIL Service, Version: 5.0.2172.1"

Date and Time
When the originator transmits a message, the Exchange 2000 SMTP service attaches the date, time, and Greenwich Mean Time (GMT) offset.

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

"Q156965 XFOR: SMTP Header Time Conflicts with Sent Time on Message" For more information about GMT, please visit the following Royal Greenwich Observatory Web site:

"http://www.rog.nmm.ac.uk/mill/meridian.htm" Additional query words:

Keywords :

Issue type : kbinfo

Technology :