When you open HTML or rich text email in Micrsoft Outlook 2013, 2010, or 2007 on a Windows 7 or Windows 8.0 based computer, Yu Gothic font multibyte characters are not displayed correctly and are unreadable.
Outlook uses the font API of Windows to display email text that has font settings. This issue occurs if the Yu Gothic font isn't installed on the computer.
To fix this issue, download and install the Yu Gothic font. After you install the font, the font file (Yu Gothic or 游ゴシック) will appear under the default path of the font library (<SystemDrive>:\Windows\fonts).
Note Yu Gothic is a new font that's included in Microsoft Office 2016. It's also included in Windows 8.1 and later versions of Windows.