Add-on / Extension for Mac Mail

We are seeking a developer to create an add-on (or extension / plugin) for Mac Mail. The extension will be quite simple in its functionality, relating to how emails are presented. A person with a good knowledge of scripting for Mac Mail is essential to complete this task. The extension will be compatible with Mac Mail versions 4 & 5. The successful applicant will be required to sign a non-disclosure agreement, as we wish the add-on to remain private until release. We require a friendly, reliable professional approach with good English communication skills. We will also require evidence of skills to complete the project, a previously created plugin would be proof of skills. Skype is an advantage. All the best!