wl177.sendgrid.net has no MX records.
Question and response
Question
dig wl177.sendgrid.net. MX
Answer
The response has no answer records.
Authority
wl177.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2397406934 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0