MS Outlook and some other ESPs can only render certain fonts. Times New Roman automatically replaces any fonts that are not standard or native to them. You can imagine what the results look like for the recipient. You’re much safer selecting a standard font from the beginning. Even if you have your own brand font, set a standard one separately for the older ESPs. The standard list includes Arial, Comic Sans MC, Courier New, Georgia, Helvetica, Lucida Sans Unicode, Tahoma, Verdana, Times New Roman, and Trebuchet MC.