Hi Hilary,
I'm working fine in my current configuration using IP 2013 + Outlook 2013 on Windows 7. But when I use the same form on a Windows 10 with IP 2013 + Outlook 2016 the envelop will not open when switching view uses the below custom VB code. I keep getting an error that I don't have Outlook 2013 as my default email client.
Me.ViewInfos.SwitchView("IMComms")
If Me.CurrentView.Window.MailEnvelope.Visible = False Then
Me.CurrentView.Window.MailEnvelope.Visible = True
Else
Me.CurrentView.Window.MailEnvelope.Visible = True
End If