All headers which were not recognized and explicitly dealt with.
This should mostly be custom headers, which are marked as X-[name].
This list will be empty if all headers were recognized and parsed.
public NameValueCollection UnknownHeaders { public get; private set; }
Remarks
If you as a user, feels that a header in this collection should be parsed, feel free to notify the developers.
See Also
MessageHeader Class | OpenPop.Mime.Header Namespace