Outlook MailItem: How to distinguish whether mail is incoming or outgoing?

Question

I am writing VSTO Outlook addin in C#, and I need to distinguish, whether given MailItem is incoming or outgoing (or neither, when it is for example a draft).

Is there some foolproof way to do this? Best solution I have now would be getting a list of recipients, cc's, and bcc's, loading email adresses from active accounts, and checking if those two lists intersect, but this seems quite fragile to me, and I hope that there is a better solution.

Use case: I'd like to get a relevant date for an email, which could be either ReceivedTime, or SentOn, but to know which one I should use, I beed to know whether a mail was sent or received.

Thank you for ideas :)