Comment Re:Outlook's icon is a clock (Score 1, Interesting) 233
If people were to use any of the KDE applications, there is a great all in one organizer application called Kontact which includes an e-mail client fully integrated into it. So yes, there are OpenSource e-mail `clients` with an appointment calendar.
As for Exchange at work, I don't know of any good program that can tie into it, only replace it completely.