Yes, Hillary Clinton is getting unjust preferential treatment due to her role as a highly likely next President of the United States. This special treatment is unjust and should not be tolerated, but it is easy for the FBI and government officials to look the other way as Clinton is an individual who is likely to come into greg power as POTUS very soon. It is unlikely that she is charged with espionage because even individuals like Obama are already making a notion at pardoning her.
Hillary is a very powerful politician with plenty of highly-placed friends. She receives special treatment all the time and uses this to her advantage. That is what any good politician is supposed to do. I am sure she has friends in the FBI who are looking out for her best interests.
I feel like Hillary Clinton is being treated just like any other politician on trial for something. They definitely give her enough grief and I believe she is going through a lot of stuff with this email scandal. She is facing tons of scrutiny and is getting a lot of grief for her exploits.
There are enough rabid anti-Clintonites around that the FBI will catch a lot of flack if it offers special treatment to Hillary Clinton. Candidates for the highest political office are (these days) given more intense scrutiny, not a "get out of jail free" card. Granted, if they can spin the process out long enough, it either won't matter (if she loses the election) or the Attorney General will drop the case (if she wins). But public opinion will be loudly voiced on the internet, either way.