We've recently started using the web client in addition to the Windows client (10.4).  We haven't been able to figure out how to "generate pages" for Outlook .MSG files in the web client like we can in the windows client.  PDF files work as expected, but not MSG files.  This has the unfortunate side effect of not being able to merge MSG files with PDF files.  If we generate pages in the Windows client, then we can merge documents in the web client without any problems.  But that kind of defeats the purpose of having the web client for my users.