I like this program a lot. I used KMail and KDE for the better part of two years, and made the switch to Evolution at the same time I switched environments to GNOME. I haven't regretted it at all, especially now that I know everything it's capable of. Well done!
The license appears to me to be pretty close to a
BSD/X11-type license, not the "other proprietary license
with source" that is shown. Note some people do filter on