Unable to get emails to display "on Befalf of", when sent using EWS API

Wayne Johnson 21

I am using the EWS API to send emails on behalf of an email address other than that of the mailbox I am using. I don't want to copy the email to the Drafts & SentItems folders of the mailbox I am send in behalf of, so I can't follow the standard advice for this. I want to keep the emails in the SentItems folder of the sending MailBox. However, when I attempt to do this via Outlook 2016,

The email is copied to the sending mailbox's SentItems
The "on behalf of text" is correctly displayed in the title.

But when I try to do this using EWS API, everything seems to work the same except the "on half of text" is not displayed. Is there another setting that controls when that text is displayed?

ChristyZhang-MSFT 20,706 Reputation points Microsoft Vendor

2022-11-29T02:25:47.643+00:00

Hi @Wayne Johnson ,

Welcome to our forum!

Looks like your issue is more related to Exchange development, please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client. In order to better solve your problem, we will add "office-exchange-server-dev" tag.

Thanks for your understanding and hope your issue would be resolved soon.
Glen Scales 4,431 Reputation points

2022-11-30T22:23:39.363+00:00

You need to post some of you code see we can see what you are actually doing
Wayne Johnson 21 Reputation points

2022-12-01T10:28:38.987+00:00

The code is so basic I really don't think it worth pasting here. The only other thing I've done that I have not said is setting the From address of the email to the other mailbox. (This is done in the UI as well.)

I have since found that the displaying of the 'On behalf of' text in the title is controlled by the header item X-MS-Exchange-MessageSentRepresentingType. When it's set 2, the text is displayed. A one displays the ordinary title. This is a special MS Exchange header that only Exchange can set up. It only affects the display and not how the email is handled, which is consistent with what I've seen.

I think I've answered my own question, but that still leaves my with the problem of getting the on-behalf-of text displayed. I hope I am wrong and someone can put me right.