Tips for preventing servers from being blacklisted

The word blacklist has been used for a long time and has different purposes in different scenarios. For example, in QQ, you can drag a guy you don't like or hate from a friend to the blacklist with the mouse, so that he can no longer harass you. However, what we call today's blacklist usually refers to a list of email addresses or IP addresses that send SPAM or other types of non-request information. This list is usually used by the email server to filter incoming emails and block items in the list. The purpose is to improve the security, integrity, and efficiency of the email system.

No one is willing to be blacklisted. Being blacklisted does not mean that you have offended or acted illegally. There are many reasons and purposes for the existence of the blacklist, including denial of direct access to user SMTP for dialing and digital user line DSL-this service will provide dynamic IP Address allocation. It can be said that using this method and sending emails through the correct email server configured by the supplier has become an inevitable choice for normal users.

The blacklist can define which items are misuse of network resources, and sometimes it is defined in a controversial way. Some blacklists include bounce messages or other automatic responses in their policies to prevent Bounce attacks or other similar problems. According to the RFC, any server must receive a Bounce Message during normal operation.

In addition, there are other blacklists that can restrict networks in some countries. In this case, a supplier uses certain policies and methods to block or reject emails from or to certain countries.

To put it bluntly, how can we prevent ourselves from being blacklisted? For this reason, we need to take a variety of measures, the most important of which must be closely related to ensuring the security of your email server, and ensure that any third party cannot use it to send emails in any unsafe way.

We recommend that you do not accept non-requested ads or other large emails sent by hosted users from your server. Do not run the "professional" spam service, delete the email addresses that reply to spam advertisements, the DNS addresses of spam senders, and services that make payments for spam ads. ensure the security of all hosts on the network, install the updatable anti-spam anti-virus tool for it; ensure that there are no spam botnets in the system; ensure that your email server is not an open relay system; make sure that your proxy server is not an open proxy. Make sure that the information provided in the domain registration service is up-to-date and complete. Make sure that all email servers receive the "send notification Bounce Message" message) don't use the services of notorious suppliers, especially when it comes to spam. If you use the service, it is possible to be blacklisted because your IP address is part of the assigned subnet. Make sure that DNS is correctly configured, ensure that the rules are consistent with the service-related rules in RFC; ensure that the email server does not send messages in disordered formats; deploy the sender policy framework (SPF) and Domain key (Domain Keys) technology for the sent information; do not promise that unauthenticated users will send emails locally or remotely; try to use secure connection SSL/TLS ).

If you feel that your server has been correctly configured and is sufficiently secure to handle spam, you can use some open relay testing tools and DNS testing tools on the Internet, to ensure that everything works as set. If any errors occur, they should be corrected before the server is put into use.