Some online retailers and service providers have this habit of emailing their would-be (or existing) customers who added something to their shopping cart, entered their email address, but then changed their mind and navigated away.
A typical email like that will have the subject line like "You forgot something in your cart. Complete your order now!".
The email body typically includes the cart contents, invitation to check out and list of accepted payment methods.
Does the fact that the email recipient added something to cart and filled their email in the form (but did not check out) create sufficient ground to not consider such emails unsolicited communication?
For the case of an existing customer, let's assume the T&C say nothing about such emails.