Am I able top get to the email headers of a message without downloading the full email message, I want to check for a certain OEM string in the message header , if I find it, I don’t need to download the email.
Yes you can, pleased use Imap.GetHeadersByUID() method.
Some servers allow you to search for particular header value:
List<long> uids = imap.Search( Expression.Header("X-Key", "substring-to-find" ));