mail16.srv6.adtraffic.org has no MX records.
Question and response
Question
dig mail16.srv6.adtraffic.org. MX
Answer
The response has no answer records.
Authority
org. 3600 SOA a0.org.afilias-nst.info. hostmaster.donuts.email. 1772275823 7200 900 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0