Hello Rob76,
The issue could be several things, and it would likely be difficult to hone in the problem without a thorough review of the infrastructure at play.
The error dkim=neutral (body hash did not verify) implies there is modification in some ways occurring during the email path to delivery. First off, have you verified that the correct key pairs are being used? Meaning, the public key published in your DNS is the correct key for the pair used with the selector in question?
In this example, is the DKIM signing done by Dynu outbound gateway, or something else beforehand?
AM
