With all the low cost options out in the business world today there is no reason not to look professional in all your outreach methods or online presences.
Having a good email address that is yours is crutual to looking and presenting a professional image.
Having an email address from AOL, NetZero, Access4Free, HotMail, Yahoo, or GMail does not persent a professional image at all. In fact you are advertising THEM! In essence they are letting you have your name or handle in exchange for your continual marketing of their brand.
Stop marketing someone else's brand and start marketing your own unique identy on the World Wide Web.