Resilience Testing

Most teams don't know their real failure mode.

Simulate a provider outage before it happens. See exactly what breaks — and watch Truncus surface the precise failure synchronously, so you never fail silently.

Test your resilience

A silent failure is the real risk

Most email APIs accept your request and return 202 — then go quiet. When the sending path has an outage, you don't find out until a customer does. The danger isn't the outage itself; it's not knowing it happened.

Truncus sends outbound through AWS SES in Ireland (eu-west-1) and confirms each send synchronously. If the path is down, you get the exact error back in the same call — not a 202 and a shrug.

What outage simulation shows you

> simulate --stream transactional --fail ses

Target:    SES (AWS, eu-west-1 Ireland)
Stream:    transactional
Affected:  Sending path down

Detection: Circuit opens after 5 failures in 60s
Response:  send_sync returns the exact provider error
Impact:    No silent failures — caller learns immediately

> simulate --stream transactional --slow ses

Target:    SES (AWS, eu-west-1 Ireland)
Affected:  Elevated latency, transient errors
Response:  Transient failures retried with backoff
Impact:    Recoverable sends drain from the durable queue

> simulate --stream outreach --fail ses

Target:    SES (AWS, eu-west-1 Ireland)
Stream:    outreach
Status:    100% of outreach sends fail
Response:  Each failure surfaced synchronously, with cause
Impact:    Campaign stops — and you know the instant it does

Why this matters

See exactly what happens to each stream when the sending path goes down

Confirm failures surface synchronously — no email is silently lost

Plan infrastructure improvements based on actual risk, not assumptions

Prove resilience to your team, your customers, or your compliance auditors

Test your email infrastructure before it fails.

Outage simulation is available on all plans.

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