How do I find out my mail server blacklisted?

A mail server can be blacklisted if it is detected sending spam or malicious emails, or if it has been compromised and is being used to send spam or malicious emails without the knowledge of the administrator.

To find out if your mail server is blacklisted, you can use one of the following methods:

1. Check with the mail server administrator: The administrator of the mail server should be aware if the server has been blacklisted and can provide information about the reason and the steps to take to remove the blacklisting.

2. Use a blacklist check tool: There are several online tools that allow you to check if your mail server is listed on a blacklist. Some examples of such tools are:

3. MX Toolbox Blacklist Check: https://mxtoolbox.com/blacklists.aspx

4. Blacklist Alert: https://www.blacklistalert.org/

5. MXToolbox DNSBL Lookup: https://mxtoolbox.com/DNSBL.aspx

To use these tools, you need to enter the IP address or domain name of your mail server, and the tool will check if it is listed on any of the known blacklists.

3. Check the logs of the mail server: If the mail server is being rejected by other servers or if emails are not being delivered, you can check the logs of the mail server to see if there are any error messages or hints about the cause of the problem. The logs of the mail server can typically be found in the "/var/log" directory or in the log directory specified by the mail server software.

With these methods, you should be able to find out if your mail server is blacklisted and take the necessary steps to remove the blacklisting.

Note: To prevent your mail server from being blacklisted, it is important to follow best practices for email security and to monitor the server for suspicious activity. Consult the documentation of your mail server software and the guidelines of the Internet Service Providers (ISPs) for more information on how to secure and maintain your mail server.