Install default mail client

[gcorona9]

Hello,
I would like to know how to properly install my default mail client to respond to craiglist postings. I have done it before but for some reason it stopped and starts asking me that my default mail client is not all the way installed. I have a Toshiba Laptop,triple core,windows 7. Please help me resolve this issue.

 

[scout_03]

do a reinstall of it