@artd2019 Currently Cloudron does not offer (a documented) "whitelist" / "allow list" function, so there is no way to guarantee deliverability of an incoming email. There is a feature request for it already that I'd encourage you to upvote. Version 6.3 coming in the not too distant future is supposed to deliver on many of the email improvements users have been clamouring for (including myself).
One thing you can do if you're not already is making sure to remove those emails from the Junk / Spam folder in order for SpamAssassin to unlearn the message as spam. Eventually after a sufficient number of them, it'll learn that those emails are not spam and will decrease the BAYES probability of it being spam.
On a related topic, you may want to consider enhancing your SpamAssassin rules list from the defaults, specifically in your case the BAYES_## rules perhaps as I have offered previously in this forum.