this video is to - Handle No MX Record Found || Email Delivery Error
The primary reason a domain might be lacking MX records is that the domain simply doesn't exist.
This video solves the problem of
How do I fix no MX record found for domain?
For a developer to correct this error,
First use the nslookup.exe to check if the Mail Exchanger (MX) record exists on the DNS server.
And If the Mail Exchanger resource record does not exist, manually add or modify the record.