Dear Support Team,
On Email configuration of my domain:
This server's IP XX.XX.XX.XX is on a blocklist.
Sorbs spam.dnsbl Zone
Why do you still use Sorbs spam.dnsbl Zone to query the server's IP?
@theompm pretty much what @jdaviescoates said. It's a service that is used by other email service providers to check the health of an IP address. Note that the status message is simply "advisory" in nature, and it does not affect Cloudron mail server at all. You can ignore it, if you don't think it's a big deal.