Hexadecimal vs. RGB Values in HTML Emails

We had a recent question in our forums regarding which clients support hexadecimal vs. RGB values so I figured I would publish the results of my research to our blog as well.

In summary, it is best to avoid using rgb(255,0,0) values when developing HTML emails. Long hex (#F00F00), Short hex (#F00) and colors (red) are supported in all the email clients I tested.