How to set a domain-specific spam policy?

This article describes how you can create a domain-specific spam policy. At first, you need to add a domain group, then add a spam policy.

To add a domain group:

Go to System > Inbound mail.
Select the inbound mail domain for which you want to create the spam policy. Select its checkbox:
Select Create Domain Group Per Domain. When the group has been added, the following message is shown:

To add a spam policy:

Go to Spam Detection > Policies > Policies.
Select Add Policy:
Fill in the name and description for the policy settings. You can copy the settings from an existing policy, for example, from the default spam policy:
Select Save Changes. The new spam policy should now be visible in the list.
Uncheck End User Visible and select Save Changes:
It's a good idea to have a separate quarantine folder for emails to a specific domain. To do this, edit a rule by selecting its Edit button:
To create a new folder, select New Folder:
Give a name for the folder.
On the Disposition tab, specify for how long the items will be kept before they'll be deleted automatically:
On the Services tab, set Include in Digest to On:
This will put the quarantined messages into the end-user digest. Save changes by selecting Add Entry.
Go to Groups and Users > Groups.
Search for the domain group you created and click on the name to edit the properties:
The following window opens up:
Go to the Filtering tab. Select the spam policy that you just created from the Spam Policy drop-down menu and select Save Changes.
Now the group entry should look as follows:
Verify that the group shows the correct spam policy.

Now this domain has its own spam policy.