Opening .msg file in Outlook for Mac 2011
For everyone in 2016 who is also looking for a free software without IAPs and similiar "problems" (MailRaider for example was free years ago):

MSGViewer is a free software, which can be downloaded via sourceforge. It does, what the name stands for: viewing / showing the content of the msg files! I just tried it after browsing for a good software that does not cost 10 Dollars or more and I can recommend it.

MSGViewer SourceForge link.

Edit:
Just had an .msg file with images inside: msgviewer is also capable of showing them.