Form notification emails not delivered to custom domain address (suspect hard bounce)

Form submissions are verified in my dashboard, but email notifications are never delivered to office@marcos-hausservice.at — not even in spam. Delivery to other addresses (Gmail) works fine, and the notification is configured correctly (email notification on new submission from any form).

My custom domain was migrated recently (A record + CNAME point to Netlify, but MX records are intentionally kept with my external mail provider and are working correctly — normal mail to this address is delivered fine). I suspect the notification address ended up on the hard bounce / suppression list after a temporary delivery failure during the DNS change.

Could you please check if office@marcos-hausservice.at is on the hard bounce / suppression list and remove it if so?

Site name: sprightly-faun-72139e
Site ID: ac01ff88-48c2-4768-a828-6d28eb846ebd

Thank you!