Verification

What This Does

Verification is the third pipeline stage. It sends filtered contact emails to the Debounce API for validation. This prevents sending campaigns to invalid emails (which would hurt sender reputation).

How It Works

Filtered contacts are batched and sent to the Debounce API
Debounce returns a status per email: deliverable, risky, undeliverable, unknown
Only deliverable and (optionally) risky contacts move to batching
Results are stored in the verified_contacts table

Verification Statuses

Status	Meaning	Action
`deliverable`	Valid email, safe to send	Moves to batching
`risky`	Email exists but may bounce	Configurable — usually included
`undeliverable`	Invalid or non-existent email	Excluded from pipeline
`unknown`	Debounce couldn't determine	Excluded by default

How To Use It

Monitoring Verification

Go to Contacts → select workspace and month
The pipeline progress bar shows verified count vs. filtered count
On the Status Page, check the Celery Workers module for verification queue depth

Manual Recovery (Without list_id)

If Debounce verification fails mid-batch and you have results in a CSV:

# Run from the server inside the backend container
python scripts/import_debounce_results.py <csv_file> <workspace> --month May --ready-only

Scope by month and status to avoid touching other pipeline rows.

Common Issues

Symptom	Cause	Fix
Verification queue > 5K deep	Large batch submitted or Debounce rate-limited	Normal for large batches — Debounce rate limits at ~3K/hour. Check VerificationBacklogSLOBreach alert
All contacts marked `undeliverable`	Debounce API key expired or billing issue	Check `DEBOUNCE_API_KEY` in backend env, verify Debounce account status
Verification stuck (no progress)	Worker crashed or Debounce API down	Check Status Page → Logs → `celery-verification`. Restart: on server, `docker restart celery-verification`
Partial results	Task timed out mid-verification	Re-run the verification stage for the affected batch. Already-verified contacts are skipped (idempotent)

VerificationBacklogSLOBreach: Queue >15K contacts (>4 hours to clear at 3K/hour)
DebounceAPIHighErrorRate: Debounce returning >10% errors — likely rate limiting

Verification

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