Email not being received: 550 Administrative prohibition

Symptoms

When sending a message to your server, the message bounces with the following error:

Message blocked
Your message to email@domain.tld has been blocked. See technical details below for more information.
The response from the remote server was:

550 Administrative prohibition

Description

Customizations to the ACL settings in the Exim configuration can cause conflicts that result in these Administrative errors. 

Workaround

Please note that cPanel has a limited ability to directly support custom Exim configurations. The server's System Administrator is responsible for ensuring that customizations to the default Exim configuration perform as expected.

Before performing any work on the Exim configuration, the following steps should be taken to ensure you have a backup of your current configuration:

How to backup your Exim configuration

The following steps can help you to locate customizations and remove them from the Exim configuration:

1. Access your server using SSH as the root user.
2. Use the following 'find' command to locate any customized ACL SMTP blocks:

   find /usr/local/cpanel/etc/exim/acls/ -type f -name "custom*" ! -size 0 -ls

3. You can use the Exim Configuration Manager to locate any customized entries by their name in the results of the above command and clear them from the configuration.