Failed emailed SMS (?RCS) message

An emailed SMS (?RCS) message that I'd sent to myself at ...@tomail.net bounced back to me w/the error message, "The response was: DNS Error: DNS type 'mx' lookup of tomail.net responded with code NOERROR DNS type 'aaaa' lookup of localhost. responded with code NXDOMAIN DNS type 'a' lookup of localhost. responded with code NXDOMAIN".  Yet, I get emailed SMS (?RCS) messages to my # all the time. What gives?