What This Error Means
This error means your domain has triggered the server's outgoing email protection limit — too many emails from your domain failed to deliver or were deferred within the last hour. The server temporarily blocks all outgoing email from your domain to prevent spam and protect server reputation.
Why It Happens
The most common causes include:
- Compromised email account — Someone has your password and is sending spam. This is the most frequent cause.
- Typo in recipient addresses — Sending repeatedly to an invalid email address triggers the limit.
- Compromised PHP script — A hacked WordPress plugin or contact form is sending spam.
- Mailing list with bad addresses — Newsletters to invalid or inactive recipients generate bounces.
- Forwarding loops — Email forwarders sending to bouncing addresses create cycles of defers.
- Autoresponder misconfiguration — Autoresponders replying to spam or invalid addresses.
How to Fix It
- Stop sending emails immediately
Continuing to send will extend the block duration. - Change all email passwords
Update passwords for every email account on your domain. Use strong, unique passwords. - Check your Sent folder in webmail
If you see emails you did not send, your account is compromised. - Scan for malware
Run a virus scan from cPanel → Security → Virus Scanner. Check for unfamiliar PHP files in your public_html directory. - Review forwarders, Email filter and autoresponders
In cPanel → Email → Forwarders and Autoresponders, remove any suspicious or misconfigured entries. - Check Track Delivery
Login to cPanel → Email → Track Delivery to identify which emails are failing and from which account.
How Long Does It Last?
The block is temporary and usually clears automatically within one hour once the failed delivery attempts fall outside the monitoring window. However, if the root cause is not fixed, it will trigger again.
For deferred emails already in the queue, the server follows a retry schedule before giving up:
| Phase | Duration | Retry Interval |
|---|---|---|
| Phase 1 | First 2 hours | Every 15 minutes |
| Phase 2 | Next 16 hours | Starting at 1 hour, increasing by 1.5x |
| Phase 3 | Until 4 days total | Every 6 hours |
The cutoff is 4 days from the first failed delivery attempt. After that, the message bounces back to the sender.
Example:
- First failure: Monday 10:00 AM
- Cutoff time: Friday 10:00 AM
- After Friday 10:00 AM, the email bounces if still undelivered.
Note: If delivery succeeds during retry, the clock resets. Do not resend repeatedly — it won't speed things up and may extend the block.
How to Avoid It
- Use strong, unique passwords for all email accounts
- Keep WordPress, themes, and plugins updated
- Do not send mailing lists - use email hosting instead
- for larger email list use a proper email marketing service (Mailchimp, SendGrid) for bulk emails instead of sending from hosting
- Monitor your email activity regularly
Need Help?
If you believe your account is compromised, open a support ticket with Nocser.net. We can check the mail queue, identify the source of the issue, and help you secure your account.
