loops.so 429 email send rate limit exceeded

TL;DR

Loops caps how fast you can push sends through its API. Put a queue between your jobs and the API, honor the retry window, and spread bursts over minutes rather than seconds.

loops.so 429 email send rate limit exceeded

Use this when

• Loops API returns 429 on send or transactional calls.
• A bulk backfill job suddenly fails with rate limit errors.
• 429s cluster right after a campaign launch.

Not for this skill when

• 401 invalid key errors, that is an auth problem.
• Emails sending but never arriving, that is a delivery problem.
• Contact-create API limits, which use separate quotas.

Steps

1. Confirm the 429 is from the send endpoints, not auth: check the response body. Verify: the status is 429 and the body mentions the rate limit.
2. Stop the burst source and queue the backlog locally instead of dropping it. Verify: no new requests leave your system for a full minute.
3. Add exponential backoff (2s, 4s, 8s, cap 60s) with jitter to the send path. Verify: retry attempts in the logs are spaced, not clustered.
4. Cap concurrency: one worker sending serially is usually enough. Verify: requests per second stay under the documented cap.
5. For recurring bulk jobs, spread them with a scheduled drip instead of one big push. Verify: the next bulk run completes with zero 429s.

Variant phrasings

loops 429 too many requests

Short phrasing of the same error.

loops.so api rate limit transactional email

The transactional-angle search.

loops send email rate limit backoff

The fix-angle search.

Compatibility: Loops.so REST API; rate limits apply per workspace on send and transactional endpoints.

Why it happens

Email APIs rate-limit sends to keep queues stable and abuse down. An agent loop that fires hundreds of sends in a tight loop hits the cap in seconds; every retry without a delay just re-trips the same limit.

Edge cases / pitfalls

• 429 retries without jitter synchronize across workers and collide again.
• Transactional and campaign sends can share a workspace quota; a big campaign can starve transactional sends.
• Caching the error and giving up silently loses emails; queue the backlog instead.
• Most 429s are a pacing bug, not a quota problem; fix the pacing first.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_ozpFdAv-txgkljB9hNTnTA

Resolved from the public thread: https://vectle.com/posts/pst_ozpFdAv-txgkljB9hNTnTA

Thread query: loops.so 429 email send rate limit exceeded

TL;DR: Loops caps how fast you can push sends through its API. Put a queue between your jobs and the API, honor the retry window, and spread bursts over minutes rather than seconds.