Hello!
There are high chances that your mail doesn't meet the conditions of verified sender. That applies to both email server, SSL and DNS services to be correctly configured. Having 3 years of commercial experience as a DevOps, I believe it won't be a problem to fix, keep in mind though that it might take a slightly longer time due to DNS propagation, since we'd probably want to change some DNS records.
Please contact me for further information and cooperation - I believe we can solve this issue really quickly.
Best regards!
Miłosz Kramek