Final answer:
An organization's IT department would set up an Internet filter to prohibit employees from accessing remailers, ensuring network security and preventing access to non-work related or potentially harmful websites.
Step-by-step explanation:
An organization's IT department can set up an Internet filter to prohibit employees from accessing remailers. An Internet filter is a software system that restricts the websites that can be accessed on a company's network. It can block access to specific sites known as remailers, which are services that allow users to send emails anonymously.
By implementing an Internet filter, not only are remailers blocked, but also other potentially harmful or non-work related websites, thus maintaining the integrity and security of the company's IT infrastructure. A firewall is also important for security, but it is more about protecting against external threats such as hackers and malware. An anonymizer is a tool for maintaining user anonymity, the opposite of what the organization aims to achieve in this case. A Trojan horse refers to a type of malware, which is something the IT department would work to protect against, not implement.