Permission to send emails to the contacts on your list is extremely important. Without permission from your contacts you risk the following:
- The emails you send may be classified as spam by ISPs or recipients.
- Violating anti-spam laws and could get sued for doing so.
- Generating complaints, resulting in IPs getting blocked at major ISPs all over the world.
- Getting blacklisted for sending spam, which could filter down to your own domain and/or your hosting provider. If this happens, your hosting provider could terminate your account and you could lose your website, email and hosting service.