Blocklist vs fraud filter: when to use each
Shopify merchants looking for fraud prevention usually land on two tool types:
- Fraud filters / risk scoring: rules and models that score a checkout or order (“how risky is this?”).
- Blocklists: explicit bans on customers you’ve already decided are bad (“never fulfill this person again”).
Both matter. They answer different questions.
What a fraud filter is good at
Fraud filters and scoring tools shine when you need to evaluate new or ambiguous traffic:
- Bot and scripted checkout patterns
- Country / IP / velocity heuristics
- One-off “smells wrong” orders with no prior history on your store
They’re weaker when the same serial returner or chargeback abuser returns under a new email. A score can look “fine” on a fresh account even when the person is known.
What a blocklist is good at
A blocklist is fraud prevention by memory:
- You (or another merchant on a shared network) already marked the customer
- You want holds or cancels before fulfillment
- You’re fighting refund abuse, repeat chargebacks, and multi-account hopping
Blox is blocklist-first: block by email, phone, address, or payment; deduplicate accounts; share signals across participating stores. Simple rules, not an opaque AI score as the primary control.
When to use each
| Situation | Lean blocklist | Lean fraud filter |
|---|---|---|
| Known chargeback / return abuser comes back | Yes | Optional secondary check |
| Brand-new shopper, no prior identity match | Weak alone | Yes |
| Duplicate accounts / email rotation | Yes (identity linking) | Sometimes |
| Bot floods / geo blocking | Supporting | Yes |
| “Cancel high-risk before ship” for known bans | Yes | Sometimes |
Practical rule: use filters to suspect; use a blocklist to enforce decisions you’ve already made, and to inherit network decisions about the same identity.
Using both without fighting yourself
A healthy stack looks like:
- Fraud filter / Shopify risk for first-pass review on unknown traffic.
- Blocklist (Blox) for confirmed abusers and network-known identities.
- Clear ops policy: what gets auto-canceled vs held vs allowed.
If your only tool is scoring, repeat offenders will keep resetting the game. If your only tool is a private one-store blocklist, they’ll hop stores or emails. Community blocklists close that gap.
Related reading
- How to block repeat chargeback customers with Blox
- Blox vs Blockify: blocklist-first vs fraud scoring
Next step
If your pain is repeat chargebacks and refund abuse (not just bots), start with a blocklist. Install Blox on Shopify.