Question and response
Question
dig apple.relay.mailchannels.net. TXT
Answer
apple.relay.mailchannels.net. 300 TXT "v=spf1 ip4:23.83.208.0/20 ~all"
Authority
apple.relay.mailchannels.net. 172800 NS ns-1186.awsdns-20.org.
apple.relay.mailchannels.net. 172800 NS ns-1660.awsdns-15.co.uk.
apple.relay.mailchannels.net. 172800 NS ns-369.awsdns-46.com.
apple.relay.mailchannels.net. 172800 NS ns-954.awsdns-55.net.
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0