Data URIs are a standard way to embed images and other binary data in HTML, and browser support is well documented on the web. (IE8 was the first version of IE to support Data URI, with a max 32 KB size per URI; other major browsers have supported it even longer.)
My question is about desktop email and webmail client software.
When building HTML email, standard practice is either to include images as attachments or load them externally (i.e. tracking images). Both of these have disadvantages (some clients list all of these attached files, while many rightly block or require user action to see external images). So, Data URI looks like a good way to go, but only if it's supported by email readers.
So, does anyone have a link to a recent study of support for this feature? Or investigated this at all? For example, here's an overview of CSS support. Client software I'd be interested includes:
Desktop (including version info): Outlook, Apple Mail, Thunderbird, Evolution, Lotus Notes, AOL, Eudora
Webmail: Gmail, Live/Hotmail, Yahoo! Mail, AOL
Mobile: Android, iPhone
I've done a more recent test at Litmus, with data URIs for inline <img>
elements and css background images.
These desktop clients do show data URIs:
These mobile clients do show data URIs:
None of the webmail clients showed data URIs.
These desktop clients don't:
These mobile clients don't: