You may have added an email distribution list address in a form's options to receive submission notifications, such as firstname.lastname@example.org. This means that all members of that email distribution list will be notified each time the form is submitted. Sounds convenient, right? But it can be inconvenient when just one member of that distribution list unsubscribes, which in turn opts out all members on the distribution list from receiving form notifications.
So, what should you do? You don't want to spend time entering 50 email addresses to send form notifications to, but you're risking using a single email distribution address. It may be best to reconsider why you wish to send form notifications to so many people in the first place.
If you have access to Workflows, you may send specific notifications to specific people based on what the contact submits in the form. If you do not have Workflows, you may want to consider creating more unique offers, so that only certain members of your team will be interested in those form submissions making it easier to only enter a few addresses to be notified.