What is the Best fonts for emails both business and corporate ?

shortly i changed my email client in office from outlook to Thunderbird since thunderbird has lots of features and plugins that makes life easy such as email alerts, inbuilt contact sync zindus and much more and while configuring the account the first doubt i came across is, is there any standard fonts size or font color to be used for emails in composing corporate or business emails though weird i am getting this doubt after 5 years in my professional life :)

Though i did not find anything so called standard to be followed in writing a business email wrt to fonts or anything but i found a whole lot of suggestions on which fonts to use and what not and other etiquette to follow while composing a corporate emails below are what to do and what not to do list i found.

1. Many suggest to use Verdana, Georgia, Times new roman, arial between 9-11pts depending on the font looks it should neither be too small or too large, i mostly prefer Verdana with 10pts for all my emails.

2. I have seen some of my friends in other company actually using fancy fonts when i accidentally got the mail in forwards it really looks odd and childish.

3. For god sake don't use red both for highlighting or as font color unless and until really needed, i really hate testing team guys in my office who use this color extensively and it is really not a good practice always use only Black or Blue, make it bold to highlight

4. Last but not least do not use downloaded fonts in email no matter how nice it looks since system automatically translates it into default font if the font is not available in his or her system and your email may look really odd, always use fonts which are in the computer by default.

whether you use aerial, times new roman or verdana there is no standard set but use some intuitive logic to look email good, decent and professional