Analysis on rejection of Exchange mail delivery

When the mail on the Exchange Server fails to be sent successfully, there is a relevant undelivered report NDR). You can find the reason why the mail fails to be sent from the NDR. The transfer status notification describes three different types of conditions: Success is 2. x. X digital code) Continuity transient failure 4. x. X digital code) a long failover failure is 5. x. X numeric code ).

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1. the IP address of the email server is included in the black outer ticket of the anti-spam organization.

In this case, an email is usually sent along with a rejected email. The content of the email indicates that the email is not successfully sent because the recipient's server has set RBL. You only need to find the relevant RBL list provider, or contact the sender's server to manually add your server to the whitelist.

2. the email server domain name is not correctly reverse resolved. Generally, Reverse Domain resolution is not required, but some receiving servers with strict requirements will detect this, it may also be caused by this problem. Currently, some popular anti-spam software may reverse parse the FQDN name sent by the mail server. connections that fail reverse resolution will be disconnected.

PS: Reverse Domain name resolution function of the email server. When this function is enabled, all messages sent from addresses without registered domain names are rejected. Currently, most spam senders use IP addresses that are dynamically allocated or do not have registered domain names to send spam emails to avoid tracking. Therefore, the number of spams can be greatly reduced if the email server rejects messages from sites without domain names.

3. the email server does not parse the correct MX record. There are many more problems with MX records. It is important for technicians to know that MX not only works when receiving emails, but also plays a secondary role when sending emails. Exchange Chinese site http://www.exchangecn.com) related domain names and mailbox records are added according to the following records. The correct parsing method is usually as follows:

4. emails caused by HELO information cannot be sent and rejected by the recipient. This situation is rare, but still exists. Some receiving servers detect the HELO information of the sending server, this problem occurs when the domain name provided in HELO information cannot be resolved, the HELO information is not a complete domain name, or the HELO information contains invalid Chinese characters.

In addition to the possibility that these Exchange Server emails cannot be sent successfully, there are many other possibilities, such as incorrect recipient address, too many recipients, and network problems, this requires technicians to pay more attention to some details in the troubleshooting process. Sometimes the negotiation is a small problem that makes the whole problem complicated.