mx03.cloud.vadesecure.com has no SRV records.
Question and response
Question
dig mx03.cloud.vadesecure.com. SRV
Answer
The response has no answer records.
Authority
cloud.vadesecure.com. 900 SOA ns-1699.awsdns-20.co.uk. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0