smtp3.fuse.net has no MX records.
Question and response
Question
dig smtp3.fuse.net. MX
Answer
The response has no answer records.
Authority
fuse.net. 900 SOA ns1.fuse.net. hostmaster.fuse.net. 3661 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0