Segments are dynamic: each time that you use a segment, Mapp Engage checks its database and selects the contacts who currently match your criteria. The current size of a segment depends on the criteria and on the data that is stored for a contact. This data changes with data that you collect about a contact.

When you calculate a segment, Mapp Engage shows you the number of contacts who match the segment criteria. However, when you use a segment for sendout, the final number of sent messages is often lower than the segment count. The discrepancy is because Mapp Engage skips some addresses with known problems during sendout. For more information, see ​Skipped Messages (tab)​.


  1. Go to ​Contacts​ > ​Segmentation Builder​.
  2. Locate the segment in the list. Next to the segment, click the  symbol.

    The calculate symbol appears only when the segment is published.

  3. Mapp Engage calculates the number of contacts in the segment. When the calculation is finished, you can see the number of contacts in the segment in the Number ofContacts​ column.

You can also limit the size of your segment. This is particularly useful if you need additional cost control. For more information see Limit Segment Size.