iCloud custom domain not receiving mail

I had iCloud with my custom domain (and two addresses) set up and everything was working fine.

I wanted to try out HEY and changed my DNS servers over to them. Ended up not liking it and set up iCloud again.

In setting up iCloud again, it seemed everything was fine, no errors in the setup.

But here’s what’s happening:

• VIA the browser, I am not able to send from my domain. Doesn’t give me the option.
• on my iPhone, I AM able to send from my domain.
• but, sending some test emails TO my custom domain, I don’t receive them, nor am I getting any errors on the sender side.