A part of my IT job I take upon myself is to sieve through outgoing employee emails to remove confidential and personal information before handing over the account to the succeeding person.
One fateful occasion, I found a strange email in the inbox with salary information that was sent from employee X to the HR manager, and in turn forwarded by the HR manager to the email account owner (who is now an ex-employee). It appears that the HR manager had sent the salary information to employee X to work on some document formatting.
This raises the alarm.
In order to obtain more evidence, I logged into their email accounts and searched for the correspondences. Eventually I ended up finding more such cases between 3 other employees, together with the HR manager. Altogether 12 cases breach of trust; 6 sowing discord; and 3 asking others to do her job.
I wanted to report on misconduct but I am worried about my unethical access. As an IT personnel, I have authorised access to all systems, but I feel I could have consulted with a director before proceeding with the search. I have no idea how the management will think/act if I reveal this. What should I consider for protecting myself while be able to do justice?
EDIT: At which level (manager, director, or a particular department) would "snooping around" be legal? Or can make a legal decision to search?
EDIT 2: The answers thus far uses the legal explanations and the simple "ask your boss". I have done a Google search and it appears that in the case where law is in place, you cannot "ask your boss". The only legal way is to ask the email owners to grant access (but I still think there is a grey area: who gives permission to view ex-employee emails?). Whereas in the absence of a law, it is not clear who has the ethical authority i.e. which boss is it?
EDIT 3: Due to the majority enthusiasm for policy of minding-my-own-business and self-protection before the law (which I must admit I find rather surprising), I feel that the answers have deviated substantially from my intended main theme of "how to bring justice" to "problem with unethical evidences".
Anyway, I do appreciate that the short answer is I cannot do anything (at least under majority of country laws). Thanks for the answers. To some of the commenters/answerers, I regret that I am unable to provide more details regarding my position in the company and the nature of the misconduct I am complaining about etc. thus making this question a bit of a guess in the wild.