How exactly are you sending this email? Is it a regular email or an automated email? Do you have a Marketing Hub Professional subscription?
If you have a Marketing Hub Professional subscription, this is easy: Simply set up a contact-based workflow that enrolls contacts from your list, then add an action to send the email. By default, workflows only enroll a contact once. Make sure that the workflow working hour settings are set to 9am to 5pm, for example, so that emails aren’t sent during the night when your list updates.
If you don’t have Marketing Hub Professional, make sure to find a unique name for your marketing email. You can then build a contact-based list and filter for contacts where the contact property ‘Last marketing email name has ever contained any of [the unique name of your email]’. This list should populate with all contacts that have ever received an email matching the specified name. You can use this list as an exclusion list in the ‘Send or schedule’ tab of the email editor. As an active list, it will auto-update each day. Make sure that your list filter is working correctly and don’t forget that the naming convention is crucial for this to work.