Error handling guidance
Error codes describe the request or account state, not the quality of the submitted address. Keep
them separate from allow, block, and review decisions in logs and analytics.
This separation matters during incidents and billing changes. A spike in invalid addresses should
trigger product or abuse review, while authentication, subscription, and usage errors should route to
the account owner responsible for API configuration and plan capacity.
Log the error code, HTTP status, request context, and retry decision together. That gives your
troubleshooting workflow enough context without confusing service issues with validation outcomes.
Authentication errors are configuration issues
A missing or invalid token should pause validation and prompt the API owner to fix credentials. It should not mark an email address as risky.
Subscription errors need account handling
Payment-required responses mean the team account cannot validate at the moment. Route these to plan review, billing recovery, or a queueing strategy.
Usage limits are capacity signals
When usage is exhausted, decide whether to stop new validations, queue them, or move to a plan with more allowance before user-facing workflows are affected.
Temporary service errors need fallback logic
A service or usage-check failure should produce a controlled fallback path. For signup flows, review is usually safer than silently allowing or blocking the address.