Have you tried configuring it using their DQS service (with an API key)? I would test that scenario, too.
I waited a long time for a reply from spamhaus, which never came, so I proceed to indicate what I did (and some doubts).
When creating the free account, if you access your Customer Portal, in Products DQS, there seems to be the data for postfix, the "Query Key" and we have this sentence:
Please review documentation and getting started guides to help you set up and access the service.
With a link to the documentation and getting started guides.
When accessing there, a series of instructions appear, and it is here where I see or think the instructions are to modify the main.cf of postfix with spamhaus.
By default, in main.cf, referring to spamhaus, we only have "reject_rbl_client" which in full is: "reject_rbl_client zen.spamhaus.org"
According to your instructions, we must replace it with:
reject_rhsbl_sender
reject_rhsbl_helo
reject_rhsbl_reverse_client
reject_rhsbl_sender
reject_rhsbl_helo
reject_rhsbl_reverse_client
reject_rbl_client
All of them, with their corresponding chain after each entry corresponding to our query key (or API key, as we want to call it, but there they call it Query Key).
Besides, there are 2 more things to do, but they don't require any major importance/relevance, create a file in postfix, put a content that refers to our query key, make a hash and insert a line in the main.cf of the hash we made.
Well, I did it, and now I receive mail from any domain (I had time to try two, just in case, I made a snapshot of my vps...).
But my question, if by default we only have the spamhaus entry for reject_rbl_client, should the others also be there? I mean the ones I put in "quote".
In case it helps someone, because thanks to this post, I saw the light, I was a while not knowing why I wasn't receiving emails...