I have the same problem with the hosting company i work with. One email account get restricted often. I use that email account to sent legitimate emails to clients, i send those emails from outlook, manually, one by one no scripts involved but after 20 emails or so, the account get restricted. I don't know why this happens because the hourly limit is set to 300. Is there an algorithm implemented in cPanel that flag accounts and restrict them automathicaly? The hosting company i work with says its cpanel faults and they cant do nothing about it.
Thank you! And sorry for my English.