I need to collect an e-signature to authorize a service upgrade.

The Idea: Upgrading subscription plans requires agreement to specific terms of service, collection of an e-signature, and confirmation email sent to the customer and shop managers.

Using Contact Form 7 streamlined form building and allowed me to develop a WordPress plugin to hook into the form submission and submits relevant data to MailJet directly via their transactional API.  Note: The e-signature is cooler on a touch device, but works with mouse input, too.

Try out the E-signature