Resilience Testing

Most teams don't know their real failure mode.

Simulate provider outages before they happen. See exactly what breaks, what falls back, and where your single points of failure hide.

Test your resilience

Fallback is not redundancy

Many email APIs route through the same underlying infrastructure. If your fallback shares the same dependency as your primary, you have two providers but one point of failure. When that infrastructure has an outage, both fail simultaneously.

Truncus maps the actual dependency chain underneath every provider. Not what they market — what they run on.

What outage simulation shows you

> simulate --stream transactional --fail ses

Target:    SES (AWS dependency)
Stream:    transactional
Affected:  Primary provider down

Fallback:  Brevo (France, independent infrastructure)
Status:    Emails continue through fallback
Impact:    No disruption expected

> simulate --stream transactional --fail aws

Target:    AWS (underlying dependency)
Affected:  SES (primary)
Fallback:  Brevo (independent — NOT on AWS)
Status:    Emails continue
Impact:    No disruption — true independence

> simulate --stream outreach --fail ses

Target:    SES
Stream:    outreach
Fallback:  None configured
Status:    100% of outreach emails will fail
Impact:    Campaign delivery stops

Recommendation: Add a fallback provider for outreach

Why this matters

Expose hidden shared dependencies before they cause real outages

Know exactly which streams survive provider failure and which don't

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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