How to distinguish inbound and outbound outlook mail items?

Question

Dear Microsoft,

Please advise what is the best way to distinguish inbound against outbound outlook mail items or please confirm if it is impossible at all.

My company uses a self-developed Outlook Add-in allowing to save a selected Outlook mail item in an external system. People can select sent or received emails to run Add-in over them. However, the further workflow in that external system depends on the type of Outlook mail item and therefore we need to know if it was received or if it was sent email.

Currently, to define the type of Mail item we use a simple logic, like: if [Mailbox owner] = [email sender] then it is Outbound email, otherwise it is inbound email.

It covers most of our needs but sometimes people send emails to themselves and then they run Add-in on inbound email which will be defined as Outbound email by the logic above.

So my question to you: is any more reliable way to find out the type of a selected Mail Outlook Item?

Answer 1

If the Add-in can analyze headers, this might be a good option.
An inbound message will have internet headers in it's properties. A sent message in outlook won't have anything in properties.