Article ID: 254560 - View products that this article applies to.
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When a telnet session is initiated to a computer running Microsoft Windows 2000 and Microsoft Exchange 2000 computer at port 25, a banner similar to the following is displayed:
220 smtp01.northamerica.corp.microsoft.com Microsoft ESMTP MAIL Service, Version: 5.0.2172.1 ready at Tue, 29 Feb 2000 18:55:48 -0600
This banner originates from Request for Comments (RFC) 821 section 3.5. The banner can be broken into four separate elements:
Reply CodeThe 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 are some related points from Appendix E:
2xy--2 as the first value denotes "Positive Completion reply."
x2y--2 as the second value denotes "Connections."
xy0--The last digit, 0, provides the option to give a finer gradation of meaning in each category.
Therefore, 220 means a connection has completed successfully.
HostIn this example the host or computer name is smtp01.northamerica.corp.microsoft.com. This means that the Domain Name Service (DNS) domain name is northamerica.corp.microsoft.com and that 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: smtp01NOTE: For clarification, a node in Active Directory and DNS 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.
Subdomains: northamerica and corp
Root Domain: com
SoftwareThe following SMTP service (software) is being used for the information in this article:
Microsoft ESMTP MAIL Service, Version: 5.0.2172.1This is the default SMTP software that is installed with Microsoft Internet Information Service (IIS) 5.0.
Date-TimeWhen the originator transmits a message, the Windows 2000 and Exchange 2000 SMTP service attaches the date, time, and Greenwich mean time offset. For additional information, please see the following resources:
Microsoft Knowledge Base article:
156965Royal Greenwich Observatory:
(https://support.microsoft.com/kb/156965/EN-US/ )XFOR: SMTP Header Time Conflicts with Sent Time on Message