If you are ok with using an external tool, "mailsend" could help:
https://github.com/muquit/mailsend . There is a link from that page with Windows binaries.
Example usage with Gmail as SMTP server:
mailsend -smtp smtp.gmail.com -to
somebody@yahoo.com -from
someone@gmail.com -sub "Hello my friend" -ssl -auth -port 465 -M "Hello again..." -user
someone@gmail.com -pass mypassword
(although in order for this to work for Gmail specifically one must go to
https://myaccount.google.com/security?p ... nectedapps and enable "Allow less secure app". But depends which SMTP server you would like to use)
mailsend -h for help
EDIT: I see now you want to use Outlook. If it is a must, then I would use something like AutoHotkey (or even cmdwiz) to wait for the window to show and then send a key-combo or mouse-press to send