Error: Domain has exceeded the max defers and failures per hour
If you see this error in your mail server logs or email management panel, it means that your domain has exceeded the maximum allowed number of failed (bounced) or deferred emails within one hour.
Why does this happen?
The system detects that too many emails have been sent to invalid, non-existent, or temporarily unreachable addresses. To protect your domain’s reputation and avoid blacklists, a temporary sending block is automatically enforced.
Block duration
⏱️ The block lasts for 1 hour. After this period, the system will automatically attempt to resend the remaining emails, provided the error rate has normalized.
Purpose of the block: protecting domain reputation
Sending bulk emails to invalid addresses is a behavior typical of spammers. If your domain acts this way, providers like Gmail, Outlook, and Yahoo may flag it as suspicious and add it to public or private blacklists.
- Emails delivered to the spam folder
- Emails rejected by recipients
- Loss of trust in your domain
