wl087.sendgrid.net has no MX records.
Question and response
Question
dig wl087.sendgrid.net. MX
Answer
The response has no answer records.
Authority
wl087.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2397368783 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0