I'm not receiving email at my custom domain.

I have a custom domain that has beens setup for months and I normally get email from various sources. Most of my spam is filtered and I've been happy with it. Now, I've stopped getting emails I send to myself either through my website (such as password reset) or from my other iCloud email address.

My sense is that everything is suddenly being caught in a spam trap and doesn't even make it to my spam folder. What can I do about this? Is there a way to whitelist senders so I always get their mail?