ns.tolna.net has no MX records.
Question and response
Question
dig ns.tolna.net. MX
Answer
The response has no answer records.
Authority
tolna.net. 86400 SOA ns3.tolna.net. support.tolna.net. 2020052878 86400 7200 3600000 172800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0