Full Answer

Meta calculates EMQ per event type by evaluating which customer identifiers you send with each CAPI event, the quality of that data, and the percentage of events that successfully match a real user profile. The identifiers that matter most are SHA256-hashed email, hashed phone number, first name, last name, city, country, and external_id. Sending all seven versus sending only email can improve EMQ by 30–40%.

Most WooCommerce CAPI plugins were built to pass minimum viable data — email address, event name, timestamp, and a value. That is enough to fire a server event but not enough for a high EMQ score. WooCommerce has all seven identifiers available at the order level — billing email, billing phone, first name, last name, billing city, billing country, and customer ID — but standard plugins do not extract and hash all of them before sending to Meta.

The performance impact is direct. EMQ below 7.0 means Meta's algorithm makes bidding and attribution decisions with data it does not fully trust. Advantage+ campaigns need EMQ at 6.0 or above to treat conversion signals as high-confidence. Below that threshold, your campaigns spend longer in the learning phase, CPAs rise, and lookalike audiences degrade because Meta cannot confidently identify who your buyers are.

Server-side tracking that extracts all available identifiers from WooCommerce order data, hashes them correctly, and sends them via CAPI consistently pushes EMQ from the 5–6 range into 7–8.5 — the difference between a campaign that stalls and one that scales.