Dashboard subscription emails are scaled poorly and unexpectedly

[KaPha]

The published dashboards look great when viewing on web but when the subscription emails are sent out, the image is scaled poorly in the email body and in ways we didn't expect. Besides iteratively tweaking the dashboard and forcing a refresh to see how the subscription emails look, what's a better way to design with predictable email output/formatting/sizing in the email body? Is there a way to specify/force an image dimension/size?