tel has no MX records.
Question and response
Question
dig tel. MX
Answer
The response has no answer records.
Authority
tel. 900 SOA anycast9.irondns.net. dnsmaster.irondns.net. 2602230953 7200 7200 604800 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0