Thank you for your post.
MagicSpam does not yet have a feature to manage spam on per-domain basis. We do have a development ticket for this feature; however, we do not have a time line in which this feature will be implemented.
Please note that in MagicSpam PRO for Plesk version, your customers have the option to manage their own spam setting on a per customer basis from their own MagicSpam user interface panel.
We hope this information helps.
-- MagicSpam Support Team --