I use HubSpot to manage emails to existing customers. The bulk of the emails are for important notifications, and customers do not necessarily wish to engage with our emails. However, I need to continue to notify our clients of important reminders, things they need to do, etc. I have tried to only provide part of the notification in the email and provide a link to the rest of it, hoping that would drive engagement. It does for most, but not for all. Some clients just don't read emails, but, in some instances, I need to prove that the communication was sent. Similar to banks and credit card companies, it would be great to obtain electronic consent to communicate to contacts via email, and doing so would protect the contact from an "unengaged" status.