mail2.braintreepayments.com has no MX records.
Question and response
Question
dig mail2.braintreepayments.com. MX
Answer
The response has no answer records.
Authority
braintreepayments.com. 300 SOA ppdns.paypal.com. hostmaster.paypal.com. 2022087322 7200 600 1209600 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0