[RKDinOKC]

Most modern browsers and email programs use html and have a basic set of fonts installed you can use that will provide similar results on any platform.
There are several available to this message board if you go to advanced. <- Comic Sans

Using custom fonts in electronic documents can be done easily if those documents are PDF.
And now you can include custom font's in HTML on web pages if the fonts you use are hosted somewhere.

Not sure if including custom fonts (hosted) is a default for html emails yet or not. Do know that if you include images that are hosted somewhere as opposed to included as attachments your message will get a higher spam score and runs the risk of being quarantined and not delivered to it's intended recipient's inbox. Assume that linking fonts will also increase the spam score. Recently went thru this with our Marketing department and they wanted to send sales emails with all kinds of fonts and graphics linked to instead of included as attachments. The difference is that virus and spam scanners can scan attachments, but can't verify whether links are changed between when an email comes in and when it is viewed so email anitspam antivirus scores messages with links as spam.