The app allows to send an e-mail to all attendees of a calendar event. The user browses through a list of calendar events for the current day. For each event he can compose a mail to be sent to all attendees.
If an event has attendees it will show an envelope with a badge indicating the number of attendees with a mail address. Simply tap the envelope and compose your mail. The e-mail addresses for the attendees and the note text from the calendar event will already be taken over by this great little app.