Because this specific file name appears on various "repack" and "mirror" sites rather than the official Foxmail website: Verify the Source: If you didn't download this from a trusted portal like PortableApps.com (official) or the official Foxmail.com
: Run the .paf.exe file to extract the application to your preferred portable device. FoxmailPortable-7.2.23.116-EN-CN-TW.paf.exe