While trying to import new subscribers, you may notice that some emails fail to be imported into your account. Sometimes this happens because the email is considered "role-based."
Some role-based emails, such as those starting with "admin@", "support@", "billing@" are on a banned list because they are not usually used by genuine subscribers. Such emails rarely sign up to lists voluntarily and are very often used for cold-mailing or spam.
Gmail addresses with five characters or less are also included on the banned list because they are also very likely invalid.
If you have a banned email address that you believe is legitimate, you may upload it via the Add a single subscriber tab.