The social cover images that are pulled using Lead Kahuna are taken at the actual size displayed. This can cause them to be rather large inside the emails.
Typicly if you are adding an image to an email you have the option to re-size the image as needed or crop it down to size.
Because we have the images in the emails tokenized you will not see them when writing the email and therefore you are not able to re-size them.
To preview how the images will display for a given contact. You can use the preview button and select the contact you would like to preview the email for. For the image to show the lead must have an image file mapped into the associated token field.
You can also send youself a test copy of the email to see how it will display. To do this, press the airplane icon in campaign edit mode, and you can select the contact you would like to preview the email for.
If you social cover images that you have imported are showing to large in your emails, you need to resize the images manually and replace the hosted link to the image for that cover in the given contacts details section.