Beginning with Microsoft Outlook 2000 post-SP1 security patch, Outlook's reading pane is secure and reading messages in the preview or reading pane is actually slightly more secure than opening messages. Choose to use (or not use) the reading pane based on your habits and needs, not because you think it makes your computer more secure.
In addition to reading your email, you can also read attachments in the reading pane; we've included attachment preview handlers on this page.
If PDF files won't preview in Windows 64-bit, see Can't open or preview .PDF attachment in Outlook for the solution. Note that, at this time, .MSG files saved to the file system cannot be previewed in File Explorer if you have 64-bit Outlook installed; it works only with the 32-bit version.
Adobe Reader 8.1 and above installs a preview handler for Outlook and Windows or you can use FoxIt.
More Information
If you want to preview additional file types in the Reading pane, you'll need to install preview handlers. Instructions for writing your own handlers along with some common file types are available in Stephen Toub's Vista and Office: View Data Your Way With Our Managed Preview Handler Framework article on writing managed preview handlers in the January 2007 issue of MSDN Magazine. (CHM format, from the MSDN Magazine archives)
Stephen Toub's preview handler editor utility: Preview Handler Association Editor
If you have an ActiveX control for a file type, see Get Preview of More File Types/Extensions in WDS 3.01/4.0 Preview Pane on Windows Xp for instructions to set it up as a preview handler.
Hi, Diane.
Just letting you and your readers know that one can address this by modifying the the MAPI Mail Previewer to use the x64 prevhost instead of the x86 one. Go to
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{53BEDF0B-4E5B-4183-8DC9-B844344FA104}
Change AppID data to "{6d2b5079-2f0b-48dd-ab7f-97cec514d30b}"
Is the Foxit previewer less likely to slow local OL Office 365 2016 from starting? The Adobe pdf add on is always getting disabled because OL says it's slowed opening OL too much. I run full Acrobat but couple of clones are installed by other application software . If i installed Reader in addition to the full Acrobat, could I specify Reader as the previewer if that's faster than full Acrobat previewer?
It would be the same viewer, but you would not the Acrobat addin enabled. (You shouldn't need it for preview - only for the extra features).
On foxit, I don't know. It can't be any worse. :)
It seems that many 64-bit versions of desktop Outlook do not include a preview handler that will allow Windows Explorer to view .msg files (the default file format that Outlook uses to save an email).
When I attach a .msg file to an email, to see whether Outlook 2013 on Windows 10 will baulk at displaying its contents, surprisingly, the Outlook previewer (ie, within Outlook 2013 email viewing pane) does display this attachment, but the same file cannot be viewed in Windows Explorer on disk.
I am told that 32-bit desktop Outlook 2013 (etc) installs a PreviewHandler for the desktop (ie, for Windows Explorer) so that .msg files will display content when View > Preview is chosen.
On a Windows 10 32-bit machine (Asus Transformer), 32-bit Office is supplied but I used the Windows Mail app. Maybe Outlook isn't supplied with this edition of Microsoft Office?
Using mail to look at the attachment fails, and the attachment is called an .eml file (odd?), asking me to look for another app or search Windows Store for one.