Error: 'From' header is missing


I'm randomly receiving back from server the following delivery error email while sending by Amazon SES and email is NOT delivered. (MaxBulk ver 8.4.6)
I have the suspect (but not sure) it happens when sending 1 email only (I sometimes do it testing purpose).
It says 'From' header is missing, but From header is there and it usually works.
What's going on?

Subject: Delivery Status Notification (Failure)

An error occurred while trying to deliver the mail to the following recipients:

Reporting-MTA: dsn;

Action: failed
Final-Recipient: rfc822;
Diagnostic-Code: smtp; 550-5.7.1 [ 11] Our system has detected that this message is not
550-5.7.1 RFC 5322 compliant:
550-5.7.1 'From' header is missing.
550-5.7.1 To reduce the amount of spam sent to Gmail, this message has been
550-5.7.1 blocked. Please visit
550-5.7.1 ... nCompliant
550 5.7.1 and review RFC 5322 specifications for more information. f6si1163530eda.157 - gsmtp
Status: 5.7.1