Dynamics 365 has some powerful marketing tools and extensions that can be used to email your clients on demand or based on a schedule. This is a great way to attract more business from your existing clientele or from new leads. However, not everyone wants to receive marketing emails and you certainly don't want to be known for spamming your Dynamics 365 Contacts and Leads. Luckily, we have the option to configure a Contact or Leads preference if they do not want to receive these emails.
Once configured for each Contact or Lead, Dynamics 365 will not allow you to email that person.
Unfortunately, this isn't always obvious to an end user if they are sending custom emails. While Dynamics 365 will prevent the email from sending, the notification isn't too clear.