Why some contacts won't receive an email

404 Emails never sends marketing email to a contact who:

• unsubscribed, by link, by the inbox's unsubscribe button, or because you changed them;
• had an email hard-bounce (the address doesn't exist);
• marked one of your emails as spam;
• hasn't confirmed their signup yet, if the form used double opt-in.

The campaign's audience step shows these as "Will be excluded", with the reasons. This protects your sender reputation and is required by law for unsubscribes.