Which Graphic Formats Are Best?

Format:

For text and other graphics, particularly those with sharp edges or thin lines, we recommend using .png format (alternative: gif).

For images of people, landscapes, etc. we recommend using .jpeg files.

Size:

It is best to upload images in the size that you want them to be in the mailing. This way, they don't need to be scaled and will remain sharp. 

Otherwise: Scaling up is worse than scaling down, so it's better to upload an image that is too large rather than too small.