As part of our defence against spam, we have a limit on the number of deferred or failed emails per hour sent from our mail servers, this limit is 25%. You may be wondering what this means? In essence, if 25%+ of emails sent from your domain name within a one hour period bounce back, all email from your account will fail for the rest of that one hour period.
This protection assists where one’s service has been compromised and is silently sending spam (which often is very hit and miss resulting in many failures), so you’ll be instantly aware something isn’t right. And it assists web admins in pruning their mailing lists which may have high numbers of now inactive email addresses.
If you’re encountering this issue and you’re not sure exactly what is causing this, you can probably determine the cause by using the Email Trace option in your cPanel:
- Log in to your cPanel service.
- Click the Email Trace icon.
- Enter the recipient’s email address in the text field.
- Click Run Report.
This will provide back data regarding your search term.
If you enter nothing for the recipient email address, you’ll get back data for all email traffic, and as you look through it you should see groups of bounced messages which can help you determine what sender caused the problem, and why. They will typically be emails sent to email addresses which you’ve not seen before, often (AOL, QQ.com, yahoo), and the subjects will typically sound like spam.