Please see the standard Apple EULA
NōtoMe does not store the contents or subject lines of emails you send. We do have logs of the metadata of each email - including the recipient email address - for analytics and anti-spam purposes.
You do have to create an account with an email address to use NōtoMe. Currently, all payments are handled through the Apple App Store. We use a tool called RevenueCat to help us manage the relationship between the app and the App Store, but RevenueCat does not receive any users' email addresses or any information about sent emails.
NōtoMe will not sell your contact information.