_spf.silknet.com has no MX records.
Question and response
Question
dig _spf.silknet.com. MX
Answer
The response has no answer records.
Authority
silknet.com. 10800 SOA main.wanex.net. hostmaster.wanex.net. 2026011502 28800 7200 1209600 10800
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0