Certain Customer Specific Spam submissions from Symantec Messaging Gateway (SMG) may be considered "Not valid"
The following error may be shown when checking the submissions detail:
"[Error 256] Submission invalid: message is not RFC 5322 compliant"
Example of the page with error:
Certain MIME parts of the message(s) are not conform to RFC 5322.
This problem may occur when certain MIME parts of an email message submitted as false negative/positive are not conform to RFC 5322.
How to check
A good way to check whether the samples do properly conform to the RFC is to submit the message/sample through an online MIME validator, such as http://www.mimevalidator.net.
Example of a non-RFC compliant message returned by MIME validator
The following is an example verdict returned by the MIME online validator when a message is not RFC compliant:
Errors: line exceeds 1000 characters, MIME syntax violation
(line 10) MIME syntax violation: <MIME error: ',' expected>
(line 16) line exceeds 1000 characters: (at column 1368)
Any non-RFC 5322 compliant message will not be submitted to Symantec.
It is therefore recommended that all MIME parts that are not conform to the RFC are fixed before submitting the sample as a false negative/positive again.
For more info on RFC5322: http://tools.ietf.org/html/rfc5322