Trojans are malicious applications that pose themselves as legitimate software in order to trick users to install them. Once on the victim's machine, it may run any number of malicious process to steal vital information or inflict damage to other software.
From the doc: 'a program that sends the copies of all outgoing emails. SER monitors outgoing traffic of email client software and intercepts all sending emails. Then program sends out intercepted emails to specified email addresses. Stealth Email Redirector (SER) do not intercepts emails are sending from web-based email services like a www.yahoo.com, www.hotmail.com etc.'
This is a typical trojan program, with "server", "client", "server editor" etc.
A really shame that they distribute it at sourceforge.