I opened a case #2457759 that resulted in bug BNESS-6849 - this was found to be a problem in the SPF header parsing between our on premise Email Security Gateway 600, and our Essentials package for 365 (ESS). I was directed to this forum by the tech support group as they were unable to give me any insight into what the development group's progress on the above bug is.
Here is a sampling of the headers:
Final-Recipient: rfc822; email@example.com
Remote-MTA: dns; d119377a.ess.barracudanetworks.com
Diagnostic-Code: smtp; 550 permanent failure for one or more recipients
by mail.yeah.com with esmtpsa (TLS1.0:ECDHE_RSA_AES_256_CBC_SHA1:256)
for firstname.lastname@example.org; Sat, 25 Mar 2017 07:33:13 -0500