That's not my name!

Ok, I've lost my patience. I work in a large company and we email and communicate through Skype. Everyone's names are listed last name, first name. My name is Gabrielle Ashley. I sign all my emails Gabrielle or Gabrielle Ashley. I've been working with these people for years, and I'm STILL getting responses addressing me as just Ashley.

I think it's sloppy, disrespectful and makes me feel like no one cares. Most of these people I've worked with closely on projects. I've started jokingly replying with, "That's my last name, and I'm not in the military!" I'm outspoken and thought I was making a name for myself...but what can I do to get people to remember my name?