Please try the three built-in options. That will only take a few seconds, and may work instantly.
Using the MAPI option is the one I would try first with Outlook. You can try that in less time than it takes to write a reply asking for a different answer. There's no point asking for help if you don't try the suggestions; that wastes both our times.
If that doesn't work, give the sentto option a quick try.
If none of the three options work, you'll need to find out how to tell your version of Outlook to do what you want via the command line. The Stackoverflow thread I linked above shows that it is possible, but the exact details vary with versions of Outlook. That becomes a question of how to use Outlook, not Opus. This is a forum for help with Opus, and not one where we have much expertise on Outlook.
This thread may also be of use, or at least shows what you want to do was possible in an older version of Outlook. (Unfortunately, it seems Outlook keeps changing how it works, so details may need modifying, as mentioned in the Stackoverflow thread I linked earlier):
This is the official tech support area for Opus. You're already here.