Moosend Integration

3 min readUpdated June 21, 2026

Moosend is an email marketing platform with automation and campaign management tools. WP Smart Consent integrates with Moosend via API v3, subscribing opted-in contacts to one or more mailing lists in real time.

Enabling the Integration#

In the WP Smart Consent dashboard, go to CRMs & ESPs, find the Moosend card, open the Connection tab, and paste in your API key. Toggle the integration on and save. WP Smart Consent connects to your account and populates the list picker with your available mailing lists.

To find your API key, log into Moosend and go to Settings → API Key. Copy the key shown there.

Custom Fields#

Moosend stores additional subscriber data as custom fields defined per mailing list. Custom field values are sent as an array of {Name, Value} objects in the API payload.

In the Custom fields tab, add a row, select the WPSC source field on the left, and enter the Moosend custom field name on the right — exactly as it is defined on the mailing list in Moosend. These are sent inside the CustomFields array in the subscribe payload. Custom fields must be created on the mailing list in Moosend before values can be written to them.

Field Mapping#

The Field mapping tab maps WPSC fields to Moosend subscriber properties. Moosend’s subscriber model accepts Email as the primary identifier and Name as a combined full name string — first name and last name are joined automatically. Any additional fields beyond those are sent as custom fields using the destination key as the Name value in the CustomFields array.

How It Works#

Moosend’s subscribe endpoint is scoped to a single mailing list, so WP Smart Consent sends one POST per selected list to https://api.moosend.com/v3/subscribers/{list_id}/subscribe.json. Authentication uses a ?apikey= query parameter appended to every request URL rather than a header — this is Moosend’s own authentication convention.

Moosend wraps all API responses in a {Code, Context, Error} envelope. A response code of 0 in the Code field indicates success regardless of the HTTP status code. WP Smart Consent checks this inner code and logs any non-zero values as errors.

Multi-list sends use best-effort semantics — a failure on one list is logged but does not block the remaining lists from being processed.

Lists Tab#

The Lists tab is where you select which Moosend mailing lists opted-in contacts are subscribed to. The list is populated automatically from your account after the API key is saved.

Options#

The Options tab has two settings.

Update existing contacts — controls whether an existing Moosend subscriber matched by email has their fields updated on each opt-in.

Send on unchecked — when enabled, contacts are forwarded to Moosend even when the opt-in checkbox was not ticked.

Screenshot of the Moosend email marketing options tab. "Update existing contacts" toggle is on, "Send on unchecked" toggle is off. There is a tags input box, a green "Save Moosend" button, and the status shows "Inactive" in the top right.

Troubleshooting#

List not populating — confirm the API key is correct and saved. Lists are fetched from GET /v3/lists/GetAll.json after save. A wrong key returns an error in the Moosend response envelope and the list stays empty.

Subscriber not appearing — confirm at least one list is selected in the Lists tab. Check the WPSC Logs tab to confirm the opt-in event fired. Also check the WordPress error log for any per-list subscribe failures.

Custom field values not saving — confirm the field name in the Custom fields tab exactly matches the custom field name defined on that specific mailing list in Moosend. Custom fields in Moosend are defined per list and names are case-sensitive.