dns-ext-recurse.simlab.net has no MX records.
Question and response
Question
dig dns-ext-recurse.simlab.net. MX
Answer
The response has no answer records.
Authority
simlab.net. 14400 SOA ns1.megapath.com. support.megapath.com. 1734984407 7200 300 604800 14400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0