Complex sentence: The e-mail address listed on the ransom screen was suspended by its host Posteo for being a violation of its terms of use, meaning that infected users could not actually send the required payment confirmation to the perpetrator.
Split into simpler sentences: The e-mail address listed on the ransom screen was suspended by its provider, Posteo, for being a violation of its terms of use. As a result, infected users could not actually send the required payment confirmation to the perpetrator.