Statistics Glossary

Here is a useful reference as you read statistical reports. Print out this page and keep it handy while reading statistics reports in your account.

Term	Description
Sent	The total number of emails that were sent.
Delivered	Total emails sent minus bounces: the number of emails that were successfully delivered.
Bounces	The number of emails that could not be delivered, for a variety of reasons. They "bounce" back, and the system counts them and categorizes them based on which error occurred.
Readers (or Unique Opens)	The number of recipients that opened the message. They may have opened it multiple times. They were tracked as having opened the message because they downloaded images and/or clicked on a link.
Opens	The number of times the message was opened. The message was tracked as having been opened because images were downloaded. Recipients can open the same message multiple times. So Opens is always larger than Unique Opens.
Opens without images	A conservative estimate of the number of times the message was opened in text format (i.e. without downloading images).
Web opens	The number of times the Web version of a message was viewed (e.g. because someone shared a newsletter on a social network), minus Display Issues (see below)
Total opens	The sum of all Opens.
Unique clicks	The number of recipients that clicked on any links. The same recipient may have clicked on multiple links. This is the number of unique readers that clicked. Therefore, it's a subset of READERS or UNIQUE OPENS.
Clicks	The total number of clicks. The same recipient may click on multiple links, which means that CLICKS is always larger than UNIQUE CLICKS.
Non-clicking readers	Recipients that opened the message and downloaded images, but did not click on any links. We know that they opened the message because images were downloaded.
Clicking readers without images	Recipients that clicked on at least one link (which is why we know they opened the message), but did not download any images.
CTOR (Click to Open Rate)	Unique clicks divided by unique opens. It's an important indicator of the quality of the message: it indicates how many of those who opened a message also clicked on one of the links it contained.
Shared	Number of times the social media sharing icons were clicked on, regardless of whether the recipient ended up completing the social media post or not.
Display issues	The number of recipients that clicked on the link to view the Web version of the message. Typically this happens when the user was having issues displaying the message in their email client.
Unsubscribed	The number of recipients that decided to no longer receive emails from you. The fact that they unsubscribed may or may not be directly related to the message.
Complaints (or Feedback Loops)	The number of recipients that pressed the "SPAM" button in their email client to indicate that the message was unsolicited.
Autoresponders	Replies sent automatically by the receiving email client (e.g. recipient is on vacation).
Mailbox full	A type of "soft" or "temporary" bounce: the receiving mailbox is too full to accept new messages, and returns an error.
Active	Recipients that have opened a message at least once in the last 3 months (or for a longer period of time if the statistics at the recipient level are kept for more than 90 days, which is an optional setting)
Inactive	Recipients that did not open a message at least once in the last 3 months (or for a longer period of time if the statistics at the recipient level are kept for more than 90 days, which is an optional setting)
Very active	Recipients that have opened a message at least twice in the last 3 months and at least once in the last 2 months
Fans	Recipients that shared an email message on a social network by clicking on a social sharing icon that was added to the message, or that forwarded the message to a friend