Figure 1
The Conventional Email Hosting will be going thru direct from sender to recipient without any hindrance, This will also invite the unwanted spam mail to your email as well.
The Hosting will just act in as a postmaster only
Figure 2
The Cloud Anti Spam Protection will be act as a middle agent between your incoming email where it will filter the email and block it from reaching user mailbox hence reduce eyes stress reading thru unwanted email