When an email is sent to a user it will show up in the "Recent Activity" section of their contact record. Above the activity, there is a status indicator that will tell you what has happened with that specific email. Clicking on the status will reveal extra details as shown below.
Messages status can be broken into two groups:
Successful Delivery Statuses
Each of the following events indicate that the email was successfully delivered. Although some outcomes such as "Spam Complaint" are ultimately not positive, the message was delivered successfully.
Sending: We are currently sending the message and it should be delivered
Sent: Sent indicates that the Email Service Provider (ex. Gmail.com) accepted this message. It's important to note that the message could still get routed to the SPAM or Bulk folder even it was sent successfully.
Opened: The email was opened by the recipient.
Link Clicked: The recipient clicked a link in the email.
Spam Complaint: The recipient reported this email as SPAM to their Email Service Provider (ex. Gmail.com)
Unsubscribed: The user clicked the unsubscribe link in this email
Non-successful Delivery Statuses
Each of the following statuses indicate that we are still attempting or are unable to deliver the message to the intended recipient. Many times this is because the email address is incorrect and should always be your first check.
Delayed: We are trying to send the message by the receive servers might be backed-up. Don't worry! The system will automatically keep trying.
Failed: We were unable to deliver this message. If you click on the status, you will be able to see the reason that the message failed. We try and provide helpful prompts to help you know what to do. You can also expand the technical details (as shown below) if you want to see the geeky stuff, but that info is mostly for Support to help you out with issues.