atlassian-eu.mail.e.sparkpost.com has no AAAA records.
Question and response
Question
dig atlassian-eu.mail.e.sparkpost.com. AAAA
Answer
The response has no answer records.
Authority
mail.e.sparkpost.com. 900 SOA ns-1031.awsdns-00.org. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0