This error occurs when your domain’s email addresses hosted with our email services have experienced too many defers and failures when attempting to send out e-mails.
For security purposes, our firewall will block your account until the top of the hour that the maximum amount of defers and failures was reached, after which your ability to send e-mails should be restored.
This security measure is put in place to prevent large amounts of spam from being sent out, in the case that an account may be compromised; but, this can happen when sending legitimate e-mails as well. Common reasons for deferrals and failures include: the recipient address contains a typo or no longer exists, the receiving mail server has blocked your e-mail, or the receiving mail server has encountered an error.
For more information about the deferrals and failures, you can track information for all incoming and outgoing emails for your domain’s email accounts in the Track Delivery page in cPanel, which can be found under the Email tab on your cPanel home page.
Each message is contained in a row on the table, which can be filtered using the options at the top of the page. For ease of use, we recommend changing the table to “Show 1,000 Results” if you have a lot of traffic, and also change Max Results/Type to the maximum so that no messages are hidden.
To find the source of the deferrals/failures, you can either scroll down until you see some failures (red icon) or deferrals (yellow icon), or use the page filters to show only defers and failures. The bounced messages should show an error in the Result column, on the right side, that mentions your domain has exceeded the max defers and failures per hour.
After locating these bounced messages in Track Delivery, look for previous defers or failures that occurred before you received this specific error – these are likely the source of the block. An error message in the same column should tell you what happened, and you can also see information about the message, such as the sender, recipient, and the time the message was sent. Additional information can be toggled by clicking on the table icon underneath the page navigation at the top right of the page.
If the issue is on the receiving mail server’s end, you should let the recipient know to contact their email host about the error, and cease sending messages to this address until the error is resolved.