You may notice in your contact list report that some email addresses are not sendable. You may also notice this when you upload a list and you see that the Emails column has two numbers that look like this: 80 / 100.
The first number is the number of sendable email addresses, while the second number is the total number of email addresses that are in the list.
Emails may not be sendable for a number of reasons. A common reason is that the email is a generic or multi-user address like info@, sales@, admin@ etc. Addresses like these cannot be contacted through SimplyCast.
The other reasons are that the email has already been added to the Suppression list because of a Hard Bounce, Unsubscribe request, or invalid data such as blank space.