Outlook 2016
Outlook 2013
Outlook 2010
Outlook 2007
Outlook 2003
Windows Live Mail
Windows 10 Mail
Apple Mail 11
Apple Mail 10
Apple Mail 9
Apple Mail 8
Apple Mail 7
Apple Mail 5
Apple Mail 4
Entourage 2008
FYI - Entourage for Mac was last updated in 2008, so is not the most secure option.
Thunderbird
Android
iOS
Windows Phone