Opening a .msg file in Ubuntu

This is an MS-Outlook format. There is a command line tool called MSGConvert (see www.matijs.net/software/msgconv) which converts .msg files into .eml. You can open those with Thunderbird or Evolution. On Ubuntu you should be able to install the tool using from a command line. Use to convert every file in a directory at once. MSGConvert will produce copies of your .msg-files with the suffix .msg.eml. Regardless, your friend should learn how to send content properly.