You should avoid doing a copy and paste with images to your email templates as this can cause errors in whether your images display correctly or not.
To add images to your emails, please follow these steps to upload the images:
1. Click on the image icon in the editor toolbar
2. In the popup click on "Browse Server"
3. Select an existing image and then OK
4. Upload a new image - browse, set resize options then click upload
5. Click OK to use this new image
6. The image will now be available to be inserted - click OK
7. The image will now display in your email as expected
