MX-CNAME-TARGET
MX target is a CNAME
What it means
RFC 2181 forbids MX targets that are aliases. Many servers handle it, some do not, and it slows delivery.
How to fix it
- 1Point the MX at the canonical hostname instead of the alias.
Re-check after the change
DNS changes can take up to the record's TTL to be seen; use Re-run on the result page to bypass our 10-minute cache.