Really hoping this feature is available before long! Comes up on a regular basis with my clients as they need to be logging email via mobile device and creating a new email thread each time is untidy and frustrating to all involved.
NOTE: As a workaround, don’t forget that you can bcc your HubSpot Portal ID from directly within your email app e.g 1234567@bcc.hubspot.com to log the email into your CRM 