Can I use font-awesome icons on emails

You can use this website to convert the icons into images, and then simply download the images and upload them to Imgur. From there you can use <img> tags to link to the Imgur images.

Edit:

A better solution would be to host the images on your own server with the same domain as your email's domain. This will increase the chance of images automatically being displayed on your emails, as they are normally hidden until the user decides to view them.

For example, if I used [email protected] to send emails, I'd host the images on mydomain.com

You can embed them as images in your email. You can use fa2png.io which converts the font awesome icons to png of required size as well as color.

You can't use webfonts reliably in html emails. Some clients might respect and render them, but the majority don't.