We've published a follow-up post with more recent results - view it here.
We recently had a few customers approach us about print stylesheet support and whether or not they can include them in their campaigns. We weren't sure either, so we did some testing to get to the bottom of it once and for all.
What is a print stylesheet?
Quick background, print stylesheets basically allow you to set a different set of CSS rules when you print the page to the one you see when viewing it on screen. For more details, check out Eric Meyer's great intro. By specifying a print stylesheet for our newsletters, we could ensure when a subscribers prints our email they see a much more print friendly email that might use simpler formatting and even hide some elements of the email itself.
Because most email environments won't let us link to an external CSS file, we used the @media rule to specify our print only styles (more on this here). Here's a quick sample of the code we used:
As you can see, the results were quite varied. None of the web-based email environments supported the print-friendly version, but most of the desktop environments did. Ultimately, we can put this down to lack of support for the @media rule. Unfortunately, since none of the web-based environments support the use of the link element for embedding external stylesheets, the @media rule is the only option available.
From our quick tests it appears that including print styles via the @media rule doesn't do any harm in email environments that don't support it (as they are ignored completely). If you're sending an email like an invitation with specific details or any other kind of email your recipients are likely to print, you may want to consider adding a few print specific styles if it will make your email easier to read.
If any of you guys have had other experiences with print stylesheets and have anything to share, I'd love to hear it.