dash still shows evolution after changing prefered mail program

[GodNobody]

Binary package hint: unity

Even after changing from evolution to thunderbird as standard mail application in clicking on "check mail" will end up in opening evolution.

I could prevent this by just simply remove the evolution packages but I don't think that this is the right solution

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: unity 3.8.6-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
Architecture: amd64
CompizPlugins: [core,bailer,detection,composite,opengl,decor,vpswitch,move,resize,commands,grid,gnomecompat,compiztoolbox,firepaint,place,widget,dbus,session,ring,imgpng,regex,mousepoll,animation,animationaddon,wall,workarounds,wobbly,expo,fade,ezoom,scale,unityshell]
Date: Mon Apr 11 22:46:23 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha amd64 (20110202)
ProcEnviron:
 LANGUAGE=en
 LANG=de_DE.UTF-8
 LC_MESSAGES=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: unity
UpgradeStatus: Upgraded to natty on 2011-03-25 (17 days ago)