When I click a mailto: link in a web browser: “Could not perform this operation because the default mail client is not properly installed.”
eM Client 5.0.18661.0
On Windows 7 Home Premium, Internet Explorer 10.0.9200.16721
Operation also fails (silently) with Cyberfox 25 (64-bit Firefox 25) and Chrome 30.0.1599.101 m