Campaign Failed Prospects & Processing Errors
Sometimes campaign prospects are marked as 'Failed' with the error 'stuck in processing loop after 3+ recovery cycles'. This guide explains what this means and how to prevent it.
What Is a Stuck Processing Loop?
When a campaign sends an email, it creates a 'send job' that goes through these states: pending → processing → completed. If a job gets stuck in the 'processing' state for more than 10 minutes (for example, because the sending mailbox hit its daily limit or was temporarily unavailable), the system's recovery watchdog detects it and retries.
The 3-Strike Rule
Each stuck job is given up to 3 recovery attempts:
• Attempt 1: Job reset to pending, retried at next available slot
• Attempt 2: Same process — reset and retry
• Attempt 3: If the job gets stuck again, the system permanently fails the prospect to prevent an infinite retry loop
The prospect status changes to 'Failed' with the message: 'Failed: stuck in processing loop after 3+ recovery cycles'
Common Causes
1) Daily mailbox limit exhausted — If your campaign has many prospects but only one mailbox with a low daily limit (e.g., 30 emails/day), the system cannot process all scheduled jobs within the limit. Jobs queue up and repeatedly miss the sending window.
- Outside sending window — Jobs scheduled near the end of your sending window may not get processed in time. They expire and get rescheduled, burning recovery attempts.
- Mailbox temporarily disconnected — If your mailbox has intermittent connection issues during the processing window.
- Too many campaigns sharing one mailbox — Multiple campaigns competing for the same mailbox's daily capacity.
How to Prevent This
• Add more mailboxes — Distribute sending across 3-5 mailboxes per campaign. This provides more daily capacity and reduces competition for send slots.
• Reduce daily sending volume — If you have 500+ prospects and only 30 sends/day capacity, pace your campaign appropriately.
• Use mailbox rotation — Assign multiple mailboxes with round-robin rotation so if one hits its limit, others can take over.
• Check sending windows — Make sure your sending window is wide enough to process all daily sends.
• Upgrade your plan — Higher plans allow more daily sends and more mailboxes.
What to Do About Failed Prospects
Failed prospects are not lost — they remain in your campaign and can be re-enrolled:
1) Go to your Campaign detail page and filter prospects by 'Failed' status.
2) Review the failed prospects to confirm they have valid email addresses.
3) You can create a new campaign with the same prospects, or reset their status if the system allows.
4) Before re-enrolling, ensure you have enough mailbox capacity by adding more mailboxes or reducing other campaign volumes.
Monitoring
Check your campaign's event log for 'error' events with reason 'stuck_processing_loop'. If you see many of these, it is a clear signal that your sending capacity needs to be increased for the campaign volume.