I'm writing a thriller, set in 2007, and have the scenario that one person in a government building wants to access (undetected) the email of another person in that building. They are both of a senior level, and the one who wants to read the email has access to some very clever hackers/IT specialists (but can't use the CIA/FBI because it's all very illegal). I don't want enough detail to do it, just whether it is feasible and, if so, with enough hints to make it sound plausible, e.g. would the hacker have to visit the building.

Sorry of I've chosen the wrong site or thread, but it is security and I am a newbie here...