Automatic SMTP Sending Block Due to High Number of Invalid Recipients
Utixo's SMTP service is designed to maintain a high sending reputation, ensuring maximum deliverability and avoiding penalties from spam filters.
To achieve this, the system implements automated controls, including a mechanism that blocks a sender if more than 300 emails per hour are sent to invalid recipients.
Block Notification in the Control Panel
If the block is triggered, the following message may appear in the control panel:
Domain xxxxxxxxxx.smtp.utixo.net has exceeded the max defers and failures per hour (300/300 (80%)) allowed. Message discarded.
When this happens, the messages are discarded automatically to prevent spam detection systems from lowering the IP reputation.
Automatic Unblocking
The SMTP block is automatically lifted after one hour, provided the sending behavior returns to normal.
Proper Use of the SMTP Service
The Utixo SMTP service is not designed for low-quality email marketing campaigns with high bounce rates or unverified recipient lists.
For professional email marketing, we recommend using Pulse Mailier, Utixo’s dedicated mailing solution.
Manual Unblock (for root access users)
If you manage your own server with root access, you can manually remove the SMTP block using WHM terminal access:
- Log into the server via terminal
- Run the command:
cd /var/cpanel/email_send_limits/hourly_notify - Each blocked domain will have a corresponding file in this directory
- Delete the file to restore SMTP sending for that domain
