File Upload Best Practices

Once you start building messages, it is easy to accumulate a lot of files. Here are best practices for organizing your files and optimizing images.

Folder Structure

An organized file structure will help you easily find relevant files and remove outdated ones.
  • Create a new folder for each campaign. Within that folder, create folders for each type of graphic asset. For example, you may have a logo folder, a promotional messages folder, and a transactional messages folder.
  • Within your asset folders, create monthly folders. This will make it easier for you to find and delete single-use images later on.
Important: Only these characters are supported for file and folder names:
  • Numbers, 0-9
  • Letters, A-Z and a-z
  • Backslash (\)
  • Hyphen (-)
  • Underscore (_)

Image Optimization

Your goal when designing emails should be to include images that look good on multiple devices and download quickly.
  • Slice long images in emails into multiple images to decrease load times.
  • Design at a @2x ratio to account for Retina devices. For example, if your email template's max-width is 640px, set your canvas to 1280px.
  • Save images for web. As part of a @2x ratio, images should be saved at 60 to 70 percent quality and then compressed using a file compression tool like
  • Keep email images shorter than 1728px. Outlook will clip longer images.
  • The total size of your email (including HMTL and images) should be less than 102 KB to prevent Gmail customers from seeing a clipped message.