wl224.sendgrid.net has no TXT records.
Question and response
Question
dig wl224.sendgrid.net. TXT
Answer
The response has no answer records.
Authority
wl224.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2398250271 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0