What DKIM result indicates that a suspected email cannot be processed due to syntax errors?

The result that indicates a suspected email cannot be processed due to syntax errors is Neutral. In the context of DomainKeys Identified Mail (DKIM), a Neutral result does not confirm or deny the authenticity of the email; instead, it often signifies that the DKIM signature could not be validated due to issues such as syntax errors in the email headers or DKIM records.

This can happen if the signing domain has a DKIM record that is improperly formatted or if there are other formatting issues within the email itself that prevent the DKIM validation process from completing successfully. Neutral means the email might not be entirely trusted, but it is also not outright rejected as invalid.

While other results like Pass and Fail indicate a clear acceptance or rejection of the DKIM signature, Neutral allows for ambiguity in situations where the signature cannot be accurately processed, making it the correct choice for identifying issues that stem from syntax errors.