Hopefully this will clear some of this up:
An item becomes copyrighted from the moment it is in a tangible form (for example, when saved to a hard disk). In the case of individual works, this copyright currently stays in effect for 70 years after the author’s death. information from the US Copyright Office
About the giving stuff away point:
“Mere ownership of a book, manuscript, painting, or any other copy or phonorecord does not give the possessor the copyright. The law provides that transfer of ownership of any material object that embodies a protected work does not of itself convey any rights in the copyright.” quoted from the US Copyright Office
And lastly:
“In the case of works made for hire, the employer and not the employee is considered to be the author.” quoted from the US Copyright Office
It sounds as though what you are asking for may be the last item, a work for hire. If that isn’t what you are asking, then I don’t see where fan art could be claimed as yours, even if snail mailed. If someone uses your image it would infringement, but if it is a unique creationm it doesn’t sound like you could claim copyright no matter which way you obtained the image.
I usually stay out of threads like this one, but this one kind of bugged me and needed a reply.