nypop.elron.net has no MX records.
Question and response
Question
dig nypop.elron.net. MX
Answer
The response has no answer records.
Authority
elron.net. 600 SOA dns.netvision.net.il. hostmaster.netvision.net.il. 2016080802 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0