User not receive message in Outlook when MailItem.Sender changed

Question

I have mailbox "user1@somemail.com" and I manually changed MailItem.Sender field to "user2@somemail.com" and sent it to "user3@somemail.com". I discovered strange situation that i see email in "SentItems" folder in "user1@somemail.com" but "user3@somemail.com" not receive this message. I checked logs in Exchange server and i donæt see any error messages. Just for prof i did the same but not change MailItem.Sender property but used SentOnBehalf standart functionality. And "user3@somemail.com" receive it so issue not in permission. Just for check i used OutlookSpy and compare two emails(one email that i sent using SentOnBehalf standart functionality and outher email where i changed MailItem.Sender). You can see diferrences following. Can somebody say me where is my fault and why user not receive email when i change MailItem.Sender:

Answer 1

The Sender property is not meant to take a string value. You need to set it to an AddressEntry object for a user that has permissions to send from any of the loaded accounts in the current Outlook profile.

See MailItem.Sender Property: http://msdn.microsoft.com/en-us/library/office/ff869056(v=office.15).aspx