Online Services: Is It Legal to Charge a Monthly Subscription Without Email Notification

(California and Delaware, but generally online)

Hi!

• A customer purchases a service from a website as a monthly membership
• The customer enters their credit card at sign up and pays for the first month
• The customer agrees at signup (ToS) to charge their card every month to maintain the service
• The customer can cancel the membership at anytime in their account (pending month will keep going without refund but next month will not be charged)

Now, is it legal to email the customer about their charge at signup, but charge the card without email notification the rest of the time every month?
Basically, if they forget about the service, it will keep charging forever.
However, if a charge fails, a notification is sent.

Thank you!

Online Services: Is It Legal to Charge a Monthly Subscription Without Email Notification