Its very easy to open ANY file from Access
So you could have a form with a listbox listing any external files you want to view.
Then add code so when you click an item in the listbox, it is automatically opened using the default application.
That will definitely work for PDF, DOCX, XLSX an probably for Outlook EML files though I've never tried this
The attached file modHandleFiles contains a function fHandleFiles for this purpose
modHandleFiles.txt
Import the entire file to a standard module
Then run code like this from Access
Code:
Dim strFilePath As String
'set the full file path to the file you want to open
strFilePath = "c:\MyFiles\MyPDFFiles\MyExampleFile.PDF"
Call fHandleFile(strFilename, WIN_NORMAL)
Alternatively, as I said previously, a web browser control can be used for a wide variety of content - online or otherwise
Suggest you search this site or Google for how to use this control in Access
The screenshot shows one such example - ideal for PDF & perhaps suitable for Word doc?

However, I don't think Excel files should be treated in this way - they can be imported or linked to your database
When you do this, the Excel file is in effect another table
You can also import Outlook folders to Access
This site is good for linking access to other Office programs:
http://www.helenfeddema.com/Code%20Samples.htm
Good luck