Domain yourdomain.com has exceeded the max defers and failures per hour (5/5 (20%)) allowed. Message discarded
If 20% of the emails that you have sent within an hour bounced back due to the invalidity of the recipient email, the server has been configured to block all your emails until the next hour starts in order to prevent further abuses. Sending emails to non-existing and invalid email addresses is a very common practice of spammers, therefore we are unable to lift this block manually under any circumstances.
You can take the following measures to prevent the same happening again;
- Verify all the recipient email addresses are valid and existing
- Allow up few hours before trying again since you will remain blocked if you keep trying to send out emails
