After an initial investigation of this issue, I found some references from Rfc822 and Rfc5322.
Rfc822 define rules for syntax, but not requires specific fields or other data. So, empty file or file without headers meets this requirement.
In the result of rfc5322 specification analysis, I found the following:
"The only required header fields are the origination date field and the originator address field(s). All other header fields are syntactically optional."
In this respect, the ValidateMessage should post an error message for your provided file. I have logged this issue as NETWORKNET-33762 in our issue tracking system for further analysis by the development team, and will let you know once there is more information available in this regard.
It seems that the appropriate header is missing here in this case and the validation should report error at this point. Anyways, the file has already been provided to the development team against the log issue, and we’ll update you here once there is some information available in this respect.
I have analyzed your second sample file and it seems the issue is valid. Please spare us a little time to log it in our issue tracking system for further consideration by the development team. I'll soon provide you with the ticket id for your reference.