Adobe Acrobat and Microsoft Outlook work together in many nice ways. A great tip for archiving Outlook folders is to right click on them and select "Convert [Folder Name] to Adobe PDF." Then you can have all of those emails and attachments in a single PDF file and delete the folder from Outlook.
As I was preparing for my ABA TECHSHOW presentation on using PDF files with my co-presenter Erik Mazzone, it occurred to me that I rarely used an equally powerful Adobe/Outlook feature. That is the ability to select several messages from your Inbox or other folder and convert those messages into a single PDF file. Sometimes I may just want to save an email discussion that is not about a client file. And if the ultimate goal is to archive them as PDF, why bother with the intermediate step of saving them in an Outlook folder? But what if new emails on the same subject come in later? As you can see from the graphic below, not only is "Append to Existing PDF" an option, but you also can see the last several PDF files that you either created via Outlook or used Outlook to append an email to the file.