the ptr really is inconsistent. The subnet address d00b within 2a01:4f9:4b:5387::2/64 is pointing to mail.ecloud.global instead of mail2, where the first address within that /64 range is pointing. I think it’s an oversight.
Depending on product, it isn’t easy to decleare a ptr for a whole cidr. I guess I’d fix the mis pointer at :d00b::2 if its a stable address.
You can forward your mail response to postmaster@ecloud.global - very likely it directly reaches a person doing mail+dns