Mailing (SMTP via port 25) from computers of the network of HTW Dresden ist only possible via the mail servers of the HTW Dresden (central mail server and/or mail server of the faculties or institutions). The IT Service Centre was led to this measure, since in the past several times by obviously "contaminated" computers spam was sent. As a result, the HTW Dresden was run on various blacklists, resulting in disabilities in regular mail traffic.