tld.mu has no MX records.
Question and response
Question
dig tld.mu. MX
Answer
The response has no answer records.
Authority
tld.mu. 300 SOA v0n0.tld.mu. alerts.afilias.info. 1772911993 86400 7200 3600000 172800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0