Messages that are image-heavy, contain images over 250kb, or that utilize large custom font files are known to contribute to above average media bandwidth usage.

Learn more about how to optimize your images and custom fonts below.


If your message contains an image from the Listrak Media library that is over 250kb, the large file detected alert displays on the message authoring confirmation screen. This alert displays the total amount of bandwidth that the message is using as well as the file name and size of the largest image. 

Larger images may cause a slow download speed of your message for your subscribers, particularly for those opening on mobile devices. Also, this alert will allow you to better gauge the impact of sending image-heavy messages on media bandwidth overage fees that may be incurred.

In order to provide a better user experience, Listrak recommends that the total combined size of all images in a message should be under 250kb and the non-image, HTML content portion of the message to under 100kb.

Learn more about optimizing your images here.


Custom fonts uploaded through the Font Manager impact your message bandwidth as well as your month allotted bandwidth.

Generally, Web Open Font Format 2 (WOFF2) files are more compressed than Web Open Font Format (WOFF) or True Type Format (TTF) files. Try converting font files to  WOFF2 to save media bandwidth and media library space.

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