Hi @e_badajos Check out this idea here: https://community.hubspot.com/t5/HubSpot-Ideas/Allow-custom-email-activity-association-with-Deals-via-Outlook/idc-p/391787#M69811
It is now in planning for O365 Add-In per the HubSpot Product Team. Follow this thread as they will post again when it’s in Beta.