A number of fixes for users of Safari 10.0 on OSX El Capitan. Whenever a Safari user clicks a link to download a decrypted attachment, an additional Click here to continue (Download) link has to be clicked for Safari to start the download. After that the user mist manually update the filename (Unknown) in Finder to open the file.
More information and references: ae257ae#diff-06d892e505dbbe5fd32f7c66ad232ac2R2999