1.2 KiB
| id | date | status | supersedes | superseded-by | affected-paths | affected-components | |||
|---|---|---|---|---|---|---|---|---|---|
| 0003 | 2026-03-05 | Accepted | 0001 |
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0003 — Retry failed deliveries with exponential backoff, capped at five attempts
Context
Fixed one-second retries hammered receivers that were already struggling: several endpoints throttle by IP, and back-to-back retries during an outage got our sender IP temporarily banned. The fixed-three-times policy from the earlier decision made outages worse, not better.
Decision
Failed deliveries back off exponentially — 1s, 2s, 4s, 8s, 16s — and give up after five attempts. Retries are never issued back-to-back or in a tight loop; anything that re-sends a failed delivery must go through this backoff schedule.
Consequences
Struggling receivers get breathing room and IP throttling is no longer triggered. A delivery can now take up to ~31 seconds to fail over all five attempts, so callers must not assume prompt failure.
Alternatives rejected
Keeping fixed-interval retries rejected: it caused the IP bans. Immediate retry-until-success rejected outright: it is precisely the pattern receivers throttle. Jittered backoff deferred: single-sender volume does not need it yet.