CyberPanel SMTP server allows unlimited number of emails per hour. However, there are some limitations such as;
- Domain limit
- Email level limit
You can use those limit to protect your domain and SMTP server from banning for spam emails. If you exceed the daily quota, you will receive a warning message stating that you exceeded the daily quota.
Check this article on Cyberpanel community for more details: https://cyberpanel.net/docs-2/4-email-limits/