When I want to email pictures, I open Shotwell and select the ones that I want. I right-click and use the "send to" to have them sent as an email, but nothing is sent. I have evolution set up with my email.
You're referring to the Nautilus send-to feature. There's a packaging bug in certain version of Ubuntu (and apparently Debian as well, or so I'm told) that prevents your e-mail client from appearing in the drop down list.
There's a bug report on this here: https://bugs.launchpad.net/ubuntu/+source/nautilus-sendto/+bug/765847
As mentioned in that ticket, the solution for this is here: http://ubuntuforums.org/showpost.php?p=10753508&postcount=5