Web font services for email
| Service or Foundry | Email Support | Web Service | Self Hosted | |
|---|---|---|---|---|
| Google Web Fonts (free) | yes | yes | yes | |
| Webtype | yes | yes | yes | |
| Hoefler & Co | no | |||
| Fontdeck | no | |||
| Typekit | no | |||
| MyFonts | yes | no | yes | |
| Fonts.com | no | |||
| Fontshop | no | |||
| Commercial Type | yes | no | yes | |
| Fontspring | yes | no | yes | |
| Monotype Membership | yes | yes | yes | |
| Typotheque | yes | yes | yes | |
| Linotype | no | |||
| Typofonderie | no | |||
| Process Type | yes | no | yes | |
| Production Type | yes | no | yes | |
| YouWorkForThem | yes | no | yes | |
| Optimo | yes | no | yes | |
| Village | yes | no | yes | |
Licensing
Often the reason cited for not supporting email was licensing restrictions, rather than any technical barrier. Typekit was the only service that mentioned JavaScript. Others like FontShop told me that their web font license doesn't cover email, as in the eyes of their End User License Agreement (EULA) it's considered redistributing the font. Lack of support for @font-face also plays a part, email is seen as an edge case so there's not much incentive to work out a solution. Cost wise, most email licenses are based on the number of monthly opens.
Note on Monotype
Monotype own FontShop, Fonts.com and Linotype (as well as Typecast). None of their web font licenses cover email. For that you have to go via Monotype Membership, which launched in Sep. 2014. The typefaces via that service are cleared for use everywhere, including email.
Further reading
I found the book Responsive Typography by Jason Pamental really useful. Although web focused, he talks through the pros and cons of using a web font service vs. self-hosting, and outlines browser support for the different font formats such as WOFF and SVG.
Campaign Monitor also have an email specific write up, which is a good introduction to web fonts. Typewolf's, 'The Definitive Guide to Free Fonts', lists the closest free alternative to every font on Typewolf. I've used this to find email safe alternatives to Hoefler & Co typefaces (Update as of November 4th, 2015 you can use H&Co fonts in email).