i had the same problem and got CF7 to work again by updating the Configure SMTP plugin settings with the SMTP HOst, SMTP outgoing port and secure connection prefix to reflect what on my outlook account. Hope this fixes your issues too. I accessed the settings via the “Settings” link under the Configure SMTP Plugin in my Plugins page.
Got the idea from this tutorial: https://www.youtube.com/watch?v=gqju-VMkn1Y.