I have a contact form that goes to Brevo as the SMTP relay. Brevo is not able to send to my address which coincidentally is the same domain setup in Brevo. mailcow is setup as this domain. So, I do not understand why it is bouncing.
450 4.1.8 bounces-311414302-1116923369@hl.d.sender-sib.com: Sender address rejected: Domain not found
DMARC and DKIM as well as MX records are setup. I do not have a PTR record though. Could that be the issue?