How can I send a WhatsApp message to users who have not opened my mobile app recently?

Directly creating a segment that combines 'WhatsApp users' and 'Last application open > 7 days' will likely return zero users. The Last Application Open attribute is only tracked for mobile app devices (iOS/Android), never for WhatsApp channel records, so no single record satisfies both conditions.

The way to achieve this targeting is a Customer Journey, and it only works if each user's mobile app device and WhatsApp number share the same User ID. Journeys operate on User IDs, which is what lets the app-inactivity check on one record drive a message to another.

How to set it up

• Link the records first. Confirm the WhatsApp subscriber and the mobile device are registered under the same User ID. If they are not linked, the journey has no way to connect them and this approach cannot work.
• Start the journey with an entry element such as Audience-based entry, using a segment of your app users.
• Add a Condition split and point it at a segment defined as "Last application open is more than X days ago". The split evaluates the user, so a user whose mobile device is inactive takes the 'Yes' branch.
• Send the message. In the 'Yes' branch add the Send WhatsApp Message element. In its settings scroll down to Options and enable Send to all user devices, so the message is delivered to every record under that User ID rather than only the record that entered the journey. The WhatsApp element itself can only deliver to the user's WhatsApp number, so this is what reaches it.

If nobody receives the message

• Check that the users actually have a WhatsApp record under the same User ID.
• Check the WhatsApp template is approved by Meta and that Meta's messaging window and opt-in rules allow the send.
• Inspect the journey statistics for drop-offs at the Condition split versus at the WhatsApp element — that tells you whether the targeting or the delivery is the problem.