Microsoft KB Archive/840468

= Exchange 2000 Server clients receive non-delivery reports when they sending e-mail to some domains =

Article ID: 840468

Article Last Modified on 10/26/2005

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APPLIES TO


 * Microsoft Exchange 2000 Enterprise Server
 * Microsoft Exchange 2000 Server Standard Edition

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SYMPTOMS
Microsoft Exchange 2000 Server clients may receive non-delivery reports (NDRs) that are similar to the following example when they try to send Simple Mail Transfer Protocol (SMTP) e-mail to some domains:

>Your message did not reach some or all of the intended recipients.

>

> Subject:

> Sent: 5/24/01 6:41 PM

>

> The following recipient(s) could not be reached:

>

>  on 5/24/01 6:41 PM

> Your mail system could not find a way to successfully

> communicate with the destination system. Please notify your

> administrator.

< .com

> #5.5.0

Note SMTP e-mail is also known as Internet mail.



CAUSE
Typically, this problem occurs if the destination SMTP e-mail server performs a reverse lookup and one of the following conditions is true:
 * The IP address does not match the domain name that is used in the return address of the e-mail message.
 * No pointer (PTR) record exists for the source SMTP e-mail server's IP address.

For example, the domain name that is used in the return address of the e-mail message is, and you send an e-mail message to a different domain. If the destination SMTP e-mail server is performing reverse lookups on incoming e-mail messages, and the PTR record for the  domain does not exist or is incorrect, the destination SMTP e-mail server does not deliver the e-mail message.



RESOLUTION
To resolve this problem, you must create a reverse lookup zone PTR record on the DNS server that is responsible for the source e-mail server's e-mail domain. If a third-party ISP hosts your DNS records, you must contact your ISP to verify you DNS configuration or to change your DNS configuration.

If a local DNS server hosts the DNS records for your computer that is running Exchange 2000 Server or Microsoft Exchange Server 2003, you can add a reverse lookup zone PTR record manually.

For more information about DNS and about reverse lookup zones, visit the following Microsoft Web site:

http://www.microsoft.com/windows2000/en/server/help/default.asp?url=/windows2000/en/server/help/sag_DNS_und_ReverseLookup.htm



MORE INFORMATION
You can configure your SMTP e-mail server to perform reverse lookups on incoming e-mail to make sure that the IP address and the fully qualified domain name (FQDN) of the sender's e-mail message server match the sender's domain name.



STATUS
This behavior is by design.

