Who am I ??

I'm a red boy,but I'm not a communist.
My friends wear green dresses. They love peace and harmoney.
Another friend wears gray dress. He is so flexible that he never sees things in a Black and White way.
I might be the most stable one leg standing object in the world.
I didn't budge an inch even when the great earthqake struck Japan on March 11.
I'm a red boy,but I'm not a communist.
I love green because it's a colour of harmony.
I love gray because it's a colour of flexibility.
I love my color red because it's a colour of the Sun, the source of energy.
I'm very comfortable with who I am and the place I was assigned.
I like helping people with their communication.
That's the reason I'm here in the world.
I'm the mailbox.