Your provider has special software that detects suspicious mail and put them in spam. That will be reflected in the web client of the provider as well as in your TypeApp folders.
For emails your provider may not have marked as spam, TypeApp has implemented a Block List.
To view or remove addresses from the Block List in TypeApp, please tap More (o o o) | Various Account Settings | select the account | Block List
In the Block List you can see the Addresses and Domains you have Blocked and you are also able to Unblock a Sender by removing those Address or Domains.