www.frontiernet.net has no MX records.
Question and response
Question
dig www.glb.frontiernet.net. MX
Answer
The response has no answer records.
Authority
glb.frontiernet.net. 60 SOA mgmt-gtm01.roch.ny.frontiernet.net. hostmaster.mgmt-gtm01.roch.ny.frontiernet.net. 2026021802 10800 3600 604800 60
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0