Bersoft Private Email can run on Linux (either installing it or as a portable application), using Wine (a Windows emulator for Linux).
If you run Linux, install Wine from your Linux repository to be able to run Bersoft Private Mail (and other Windows applications).
Notice that Bersoft Private Mail may work in Wine on OS X, but it has not been tested there.
Some settings will not be modifiable:
Preferences->Email CheckingTab->Show New Email Notifications: Always will be Centered in the Screen.
View->Visual Styles (in Main window): Always will be set to Windows.
The off-line help file will not work, online help will be used instead.
Some visual elements may not be drawn perfectly. Some items may not be correctly selected and unread mail may not be correctly highlighted.