A long time ago, I worked on developing Magellan, an outlook-like client for Linux/KDE. I worked on front-end and some backend stuff (until the back-end moved to CORBA that is). I also did the art (icons, gui...) for it.

Here are some screenshots:

The email interface

The email interface supported POP3 and IMAP.

Interface for contacts

The contacts component was aware of the v-card format.

Notes

We had a sticky notes interface, with popup borderless windows!

Maybe at some point I'll write more about it, because it was cool 😄