Just in order to keep this issue updated -- this has been my ActiveX previewer config for quite a while:
I have Outlook 2016 installed.
The Windows MAPI 32-bit Previewer that is selected for previewing Outlook *.msg files in Dopus works quite well and shows the contents of the *.msg files in WYSIWYG format, which is good.
However, as I have found out and cross-checked in the meantime, in order for the Outlook *.msg previewer to work, there must be Internet connectivity. If your internet connection is slow or unreliable, it can take some dozen seconds before the preview appears.
This can be tested by putting your device in Airplane Mode, in which case all *.msg file previews appear instantly. Outlook (or the relevant DLL file) seems to notice when you have no network connection whatsoever, and in this case doesn't wait for a connection with your mail server but instead just shows the file as is.
This of course would be the desired standard behavior for a preview handler.
Therefore it would be great if in Dopus it were somehow possible to cut off the preview handler from any network access, which could make Outlook Preview so much faster and more reliable.
Alternatively, if that should not be possible, maybe some adjustments to the handling of file previewers could be made. Currently, unfortunately, when you click on a *.msg file in Dopus and your internet connection is bad, it not only takes a long time until the preview appears in the preview pane, but also Dopus is nearly completely frozen during that time.
One possible way this could be improved could be the way that UltraSearch handles this. There, when you click on a search result that is, for example, a *.msg file, UltraSearch's preview pane instantly would only show the MSG file's metadata. If after a few seconds or half a minute, the Outlook preview handler has established connection with the mail server and thus reads the contents of that *.msg file, UltraSearch's preview pane would simply switch from the display of the *.msg file's metadata to displaying it's actual contents.
IMHO this is a great way to handle the Outlook preview handler's timeout limitiations, and it also prevents the previewing program from getting frozen or blocked until the preview appears.
Thanks very much for considering this as a feature request.
Best regards
David