Returns how many contacts match a predicate tree, without returning the contacts themselves. Useful to
preview the size of an audience before paging through POST /contacts/filter, or before creating a segment.

The filters payload is exactly the same as POST /contacts/filter — see that endpoint for the full
predicate documentation. Omit filters to count every contact in the app.

Response

Besides the total, the response breaks the audience down by email reachability:

• deliverable: contacts that can currently be emailed
• bounced: contacts whose email address bounced
• unsubscribed: contacts who opted out of email communications
• without_email: contacts with no email address at all

deliverable + bounced + unsubscribed + without_email does not necessarily equal total, since a contact
can fall into more than one non-deliverable bucket.