Include the ability to add double opt-in when people subscribe to email marketing
we use Workbooks for email marketing and I know you are currently working on your own email visual builder similar to Mailchimp and others, which is great news. At the moment we use a combination of the Workbooks CRM (because it is so good) and the Mailchimp integration to send emails. We use Workbooks' Web to Lead form to capture new sign ups, however it is best practice to enable double opt in when people sign up to email marketing, and at present this isn't possible within Workbooks.
So this would probably involve a triggered email that gets sent upon completing the form, for people to click on a link within it to confirm their subscription. Most email marketing software providers offer this function as standard - it just means you are ensuring you have the subscriber's permission to contact them.
We will be adding this functionality into Workbooks during 2017