Though there is no direct way to print multiple email messages from Outlook 2013 at a time, but there is a tool named as Mailxaminer which can help you in executing this task.
The tool is specifically meant for forensics users and supports multiple file formats including PST file format. So what all you can do is, browse PST file into this application, select the emails you want to print, it has an option for direct print command i.e. “PRINT” so you can select it and you will get print out of all the selected emails in one go.
For more information, visit here – http://www.mailxaminer.com/