mailer.chargify.com has no NS records.
NS records for this zone are defined at chargify.com.
NS records for this zone are defined at chargify.com.
Question and response
Question
dig u13165.wl.sendgrid.net. NS
Answer
The response has no answer records.
Authority
wl.sendgrid.net. 1800 SOA aisha.ns.cloudflare.com. dns.cloudflare.com. 2397511916 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0