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Large Number of Failed Emails: Server Troubleshooting

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Problem description #

The site reports many failed verification emails or the host rejects outgoing emails, causing massive failure counts.

Symptoms:

  • Plugin reports hundreds of failed verification emails.
  • Server logs show many rejections or bounce messages.

Typical causes:

  • Mail server blocked or throttled outgoing messages (no SMTP or poor reputation).
  • Misconfigured SPF/DKIM/DMARC causing rejections.
  • Plugin triggered repetitive automated sends because verification loop failed.

Solution (step-by-step)

  1. Stop further sends: Temporarily disable email verification or put site into maintenance to prevent further mass sends.
  2. Switch to SMTP: Configure a trusted SMTP provider (WP Mail SMTP + SendGrid/Mailgun/Amazon SES).
  3. Check host mail logs: Ask your hosting provider for the outgoing mail logs — find bounce codes and reasons.
  4. Correct domain records: Ensure SPF/DKIM/DMARC are set correctly for your sending domain.
  5. Inspect plugin logs: Delete/clear queued/failed entries once sending is fixed to avoid repeats.
  6. Ask plugin author for any rate-limit or retry settings that might be adjusted.

Prerequisites

  • Host or DNS access to modify SPF/DKIM, plugin settings, and ability to configure SMTP.

Additional notes

If the failed emails were a result of a bug in the plugin that caused repeated sends, plugin author updates may already exist, check support announcements and update plugin. WordPress.org

 

Email Verification for WooCommerce