After consulting Brian I have deleted all MX records that point to names for which no address record exists, including 4 of the above. 867 records in total. Looking at CNAME and dotted address in MX records will be the next step. Note that an MX record must have a hostname that in turn has A and/or AAAA records. So MX records that contain e.g. "44.0.0.1" are not allowed. Neither are MX records that have a name that in turn is a CNAME pointer. Most mail software will probably handle those bad MX records, so I have not yet deleted them. I advise those that make use of their MX records to fix them (replace the IP address with a hostname that resolves to that address, and replace a name that refers to a CNAME with the name that the CNAME points to). Then I can check things again in some time. Rob