This is a very common question from marketers sending email campaigns. We provide a clear Delivery Breakdown of emails - right from "User segment count" to the no. of emails that were finally sent - at the bottom of the Email Campaign Info page (which you can see by clicking on any campaign on MoEngage Dashboard > Campaigns page).

The various delivery points are as follows:

1. 1. 1. Segment Count - Total number of users that belong to the segment of the campaign
      2. Users with Email - Total number of users who have an email attribute 
      3. After B/U/C removal - Number of users obtained after removing email addresses that have earlier bounced, unsubscribed, or spam complained.
      4. After Invalid/Duplicate removal - Number of users obtained after removing Invalid emails (missing "@" & ".") and Duplicate Emails (multiple users with the same email address)
      5. After FC Removal - Number of users obtained after removing emails that have crossed Frequency Capping as defined in the FC Settings.
      6. After Personalization Removal - Number of users obtained after removing emails for which the email could not be sent due to personalization failure.
      7. Sent - This is the final count of emails that have been sent.

The exact number of email removals is also mentioned in "Campaign Delivery Breakdown", as shown in the snapshot below -

Any emails you send have an impact on your IP and domain reputation. So, we must maintain a clean email sending list - free of emails that bounced, unsubscribed, or complained - which we achieve by not initiating further emails to these email addresses.