Whist speaking with a customer about the new V20.1 addins they informed me that they really miss a (We think) version 17 feature was that when you are sending an email from Outlook, you click on the addins tab and there was an 'Attach to Act! Contact' button.
This meant you could attach an email to a contact you're not sending it to or en masse attach to specific contacts whilst sending the email.
As a work around the client knows they will have to go into their sent items and add it to an Act! contact there post sending.