Changelog

Contacts — date filtering on contact export

POST /contacts/export now supports date filtering through customContactFilter, so you can export only the contacts that changed within a time window instead of pulling the full set and filtering client-side.

New filter fields (used with actionForContacts):

• modifiedSince — export only the contacts modified after this date-time.
• createdSince — export only the contacts created after this date-time.

Either can be used on its own, or combined with listId or segmentId. For example, to export the contacts that are currently unsubscribed and were modified in the last week:

{
  "customContactFilter": {
    "actionForContacts": "unsubscribed",
    "modifiedSince": "2026-10-01T00:00:00.000Z"
  },
  "exportAttributes": ["EMAIL"]
}

Both fields take a full RFC 3339 date-time: a date-only value such as 2026-10-01 is rejected, and so is a value with no timezone — pass the Z suffix or an explicit +HH:MM offset.

Note that a contact’s modification date changes on any update, not only on a subscription change. modifiedSince therefore selects contacts whose record changed in the window, not contacts whose subscription status changed in it — the example above returns everyone currently unsubscribed who was touched during the period, which is a superset of those who unsubscribed during it. Re-read emailBlacklisted per row rather than assuming every exported contact is newly unsubscribed.

Endpoint reference:

Export contacts