On 23 Oct 2019, at 12:33, Steve Matzura <numb...@noisynotes.com> wrote: > I change the DNS record for mail from A to CNAME
Don’t do that. https://tools.ietf.org/html/rfc2181 The domain name used as the value of a NS resource record, or part of the value of a MX resource record must not be an alias. Not only is the specification clear on this point, but using an alias in either of these positions neither works as well as might be hoped, nor well fulfills the ambition that may have led to this approach. This domain name must have as its value one or more address records. Currently those will be A records, however in the future other record types giving addressing information may be acceptable. It can also have other RRs, but never a CNAME RR. (An A or AAAA record is required) -- And, while it was regarded as pretty good evidence of criminality to be living in a slum, for some reason owning a whole street of them merely got you invited to the very best social occasions.
