I started using Korganizer in the past days and I am encountering an issue, whenever I need to email participants
I get the following message:

Could not launch the mail client:
 KDEInit could not launch 'kmail':
 Could not find 'kmail' executable.

In "settings" -> "details" I have set the default app as thunderbird, I also tried changing that to "KmailService" which is installed when Korganizer is installed.

That does not make any difference.

In Korganizer configuration I was not able to find any setting to set it to use thunderbird

I searched the forums and the web and the only relevant result I found was a kde bug that was closed because someone said it was a user issue and they had to set the default email client.

I am on Ubuntu 13.04 64bit

Any help would be so great.
Thank you!