In the last couple weeks, I haven’t been able to use mail:to links in Firefox or Internet Explorer (and anything that uses IE, for example FeedDemon). Instead of opening eM Client, IE continually opens windows which give an error saying that the link could not be handled because the default mail client isn’t properly installed. I don’t think I’ve changed anything related to any of the three programs lately except for routine updates, and eM Client is still the default mail client in the Control Panel and in Firefox.
Running Windows 7 Home Premium SP1, Firefox 19.0.2, IE 10.0.9200.16521, eM Client 5.0.17595.0.