Mail Composition: open all mailto links using Mail

I'm currently using Horde eMail. Under: preferences > mail composition After clicking the LINK: "click here to open all mailto: links using Mail" I quickly realized I didn't want this on. It takes over ALL other programs: gMail and TopProducer (a REALTOR themed CMS) The PROBLEM: I cannot find a way to turn this off. I could not find an OFF link or a RESET for that feature. I'm not certain if I would have to look in Chrome to remove the permission. Any help is appreciated.