Why do the 'Segment Size', 'Reach', and 'Sent' numbers in my email campaign statistics differ?

It is normal for the numbers for Segment Size, Reach, and Sent to be different. Each metric represents a distinct stage of the campaign sending process.

Here is a breakdown of what each number means:

• Segment Size: This is the total number of devices (e.g., email addresses, mobile push tokens) that match your segment's filter conditions at the moment the audience is calculated. If your segment does not specifically filter for email, it may also include mobile or web devices.
  • Tip: To get a more accurate estimate for an email campaign, add a filter condition like Platform is Email to your segment.
• Reach (Users): This number represents the total count of unique users (UserIDs) targeted by the campaign. A single user can have multiple devices associated with their profile (e.g., two different email addresses). Because of this, the Reach (user count) is often lower than the initial Segment Size (device count).
• Sent: This is the final number of emails that were actually sent. This number can differ from the Segment Size for two main reasons:
  1. Pre-send Filtering: Right before sending, our system automatically removes any invalid email addresses. This includes users who have unsubscribed, addresses that have previously bounced, or those marked as spam.
  2. Multiple Emails per User: If a single user (UserID) has multiple valid email addresses associated with their profile, they will receive a message at each address. This can cause the 'Sent' number to be higher than the 'Reach' number.

Example Scenario: 

1. Your segment initially contains 2100 email devices. 
2. These devices belong to 1750 unique users (UserIDs). This is your Reach. 
3. Before sending, the system finds that 100 emails are invalid (bounced/unsubscribed). It also finds that some users have 2 valid email addresses. 
4. The final Sent count becomes 1900, as messages are delivered to all valid email addresses for the 1750 users.