Campaign Stuck Sending
Resolve campaigns stuck in sending status
Campaign Stuck Sending
A campaign that remains in "Sending" status longer than expected can be concerning. This guide explains why this happens and what you can do about it.
Normal Sending Duration
Before assuming something is wrong, understand that sending time depends on several factors:
- Audience size — A campaign to 100 contacts sends in seconds, while 100,000 contacts may take 30–60 minutes or more.
- Send Time Optimization — If STO is enabled, the campaign will remain in "Sending" status for the entire delivery window (12, 24, or 48 hours). This is expected behavior.
- Rate limiting — Mailnaptic throttles sending to protect your deliverability, especially for newer domains still building reputation.
- Domain warmup — If your domain is in a warmup phase, daily volume limits apply and may cause sending to spread over time.
Identifying a Genuinely Stuck Campaign
A campaign may be genuinely stuck if:
- STO is not enabled and the campaign has been sending for more than 2 hours for a small audience (under 10,000 contacts).
- The "Sent" count on the campaign detail page has not increased in the last 15 minutes.
- The campaign progress bar has not moved despite waiting.
Common Causes
Stalled Recipients
Occasionally, individual recipient records can become stuck in a "processing" state due to a transient system issue. Mailnaptic automatically detects and recovers these stalled recipients every 10 minutes by resetting them to "pending" for reprocessing. In most cases, this self-healing mechanism resolves the issue without any intervention.
Domain or DNS Issues
If your sending domain's DNS records have changed or become invalid since the campaign started, email delivery may fail silently. Navigate to Domains and verify all authentication records are still valid.
High Bounce Rate
If a campaign encounters an unusually high bounce rate early in the send, Mailnaptic may slow down or pause sending to protect your reputation. Check the campaign's bounce count relative to the sent count.
What You Can Do
- Wait 15 minutes — Mailnaptic's automatic stall recovery runs on a 10-minute cycle. Many stuck campaigns resolve themselves.
- Check campaign details — Look at the sent vs. total counts and the last activity timestamp to understand whether sending is progressing, even slowly.
- Review your domain status — Ensure authentication records are valid and the domain is not flagged.
- Contact support — If the campaign has been stuck for more than an hour with no progress, reach out to support with the campaign ID for investigation.
Preventing Future Issues
Keep your contact lists clean to minimize bounces, maintain valid DNS records, and avoid sending to very large segments without proper domain warmup. Regularly check your deliverability dashboard for early warning signs of reputation issues.