_spf.smtp.mailtrap.live has no MX records.
Question and response
Question
dig _spf.smtp.mailtrap.live. MX
Answer
The response has no answer records.
Authority
mailtrap.live. 1800 SOA graham.ns.cloudflare.com. dns.cloudflare.com. 2396631759 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0