BTW, I noticed that your error messages has a fullstop at the end: firstname.lastname@example.org. maybe this could be a problem? But it might also be just an added fullstop from the server.
However, I cannot completely exclude that Adobe's mail system might sometimes filter out emails that come from "looks like spam" email accounts like email@example.com. So, that might be a reason why some emails might not come through to us.
Please feel invited to send me an email directly (my last name at adobe.com), and I will check with the teams.