In MS Outlook (not Outlook Express) it is possible to create message rules with an action to pop up a message box, with the option to open the email that triggered the message. If you have several messages so triggered, they just get piled up in a listbox until dismissed by the user. This is a fantastically useful feature (a great way of not missing important emails) that is sorely missed in MS Outlook Express, so it would be great if Claws supported this feature.