I’m not a designer or typographer, or even much of an artist, but even I know that it’s unimpressively amateur to use Comic Sans in a professional setting. And even worse? Using it in bright colours at 16pt.
If I had the time and learned the skills to do graphic/web design or the like, I would delve into the beautiful world of typography and fonts and use it for good. I know that Comic Sans is a mortal enemy of these professions and an insult to their trade. Friendliness and warm rapport are established through words and not font. If you don’t think tone can be interpreted through text than you aren’t very good at reading between the lines, nor are you a very good writer. I don’t mean that in a belittling way. There are ways to improve, and everyone is capable. Change your font to something less ridiculous then practice, practice, practice. Improve the quality, not necessarily the quantity, of your vocabulary and always strive for mastering English grammar. Ask for another set of eyes to skim through your work. Even just an e-mail, if it’s intended to develop a relationship or provide instructions or explain something, get somebody to look over it. And change the font.