French laws say that you can use your professional mail account to send private mails.
But if you want to keep the privacy of this mail, its subject has to contain a mention about this privacy (with the word "Perso" or "Privé", for instance).
The problem is when you received mails from other people, you have to rename them manually.
How to add a button to do it in one click in Outlook?
With Outlook, you can create your own script. Here is how to do it.
Copy and paste this code :
Sub renamePerso()
For x = 1 To Outlook.Application.ActiveExplorer.Selection.Count
Set obj = Outlook.Application.ActiveExplorer.Selection.Item(x)
If obj.Class = OlObjectClass.olMail Then
obj.Subject = "[PERSO] " + obj.Subject
End If
Next x
End Sub
To add the "[Perso]" mention at the beginning of the subject of an email (or a couple), you just have to :
If, after your reboot, you can't use your macro again, you have to check your security settings.