Data URIs are dangerous. So, yes. However, your email provider probably strips links to data URIs. I know that Google & Microsoft both do. Firefox and Chrome a

Data URIs are dangerous. So, yes. However, your email provider probably strips links to data URIs. I know that Google & Microsoft both do. Firefox and Chrome also heavily restrict what can run in a Data URI, and that changes whether its embedded in a page, or opened by a link, or opened by pasting into the URL bar. However, they are still, occasionally, the source of CVEs.