Sent

Total amount of supporters that were sent the email blast.

Opened

Total amount of people who opened the email. We only count an email open from a particular email once.

Clicked

Total amount of clicks from an email to an external link.

Deferred

Total number of emails that have been deferred/throttled by the ISPs (internet service providers) and are awaiting delivery. A deferral occurs when an ISP is for some reason not ready to accept email from your IP address. Emails will generally get through eventually but it'll be over time, depending on different ISPs and how they handle bulk messages. If you are seeing this same error consistently over an extended period of time, and you feel that your policies and practices comply with the recommended best practices, you can read more about deferred emails here. 

Bounced

Things like "user is over quota" or "mailbox temporarily disabled" will cause emails to bounce. With any address we will allow two of these sorts of bounces in a row (i.e. without a "good" delivery) and then mark the email address as bad.  

Bad

There's certain classes of bounce which mark an individual email address as bad, like the error "No such user at this address." Those will instantly mark the email as bad, and if the user has no other good emails then they will stop receiving emails from that nation entirely.

If an import re-imports a given address, and that address is marked as bad, then it does not get marked as good again by the act of importing. You need to do this manually by editing the signup.

Unsubscribed

People who have clicked the unsubscribe link at the bottom of your email and opted out from further email communication. If an import re-imports a given address, and that address is marked as unsubcribed, then it does not get marked as good again by the act of importing. Do not email these users again, as that may result in your IP address being blacklisted by the spam filters.