How to work with System Locked rules
Locked rules, identified with (Locked)
in the rule name, are rules that cannot be disabled or removed from the Message or Connection Rules list.
By default, there are three Locked Connection rules which are described in this article.
(Locked) DHA
The (Locked) DHA Rule checks whether a valid email address is configured in the Mailboxes section of the dashboard. If the email address does not exist, either as a primary or alias, then the message will be rejected.
To automatically add email addresses to the Mailboxes section you can use Active Directory or Azure Entra ID synchronisation. Please see the following KB article for further details:
https://help.clouduss.com/settings/active-directory
If you prefer to manually add email addresses to the Mailboxes section, you can follow the steps in this article:
https://help.clouduss.com/ems-knowledge-base/adding-an-alias-to-a-primary-mailbox
(Locked) Spamhaus
Commercially available blacklists of IP addresses known to send spam. This includes the XBL, SBL and PBL.
(Locked) Spam RBL
Commercially available blacklists of IP addresses known to send spam.
Troubleshooting
Both of these rules aim to stop the likes of known spambots and spammers at a connection level from sending spam to your organisation. If you believe that an IP address is being rejected incorrectly, you can add the IP address to the Spam Safelist.
It is recommended to use the following sites to discover why a particular IP address has been blacklisted:
https://mxtoolbox.com/blacklists.aspx