Mac users - If you need to open Microsoft Outlook emails and attachments that are saved in .msg format, you either need a computer running Microsoft Outlook (available for Windows PC only) or buy a copy of Microsoft Entourage 2008 for Mac that can possible open MSG files.
The other solution is that you buy a copy of virtualization software like VMware or Parallels Desktop that would let you run Windows on a Mac. You can then install either Microsoft Outlook or Windows Live Mail (formerly Outlook Express) on your Mac and can then easily open MSG files.
Outlook MSG File Viewers for Mac
MsgViewer is a free utility that lets you view the content of Outlook .msg files on Mac and the email message can be saved in either RTF or HTML format. MsgView works with msg files created using Outlook 2003.
If you want to batch convert a bunch of msg files for reading on your Mac, try MSGConvert - This is a PERL script that will turn all your MSG files into one MBOX file though the formatting in individual email messages will be lost.
Alternatively, if you don’t want to invest in software just for reading a msg file, download MailRaider - this Mac software can extract text out of any msg file though it is very likely to remove all the formatting from the original Outlook message.
You cannot use MailRaider to save email in MSG files since its only a reader for MSG and not an editor. You launch MailRaider by double clicking on the application icon, or by double clicking an .msg file on your Mac generated by Microsoft Outlook for Windows. If you launch it by double clicking on the application, then you will need to open the .msg file by selecting the File -> Open.