Bad value for attribute href

The validator is getting me this error, regarding the email sharing anchor of your plugin:

Bad value mailto:?subject=Quanto vale il mio sito&body=http://www.marcopanichi.com/blog/quanto-vale-il-mio-sito/ for attribute href on element a: Whitespace in query component. Use %20 in place of spaces.

http://ww.wp.xz.cn/plugins/social-sharing-toolkit/