将XML文件作为附件发送电子邮件时，对Content-Transfer-Encoding感到困惑

I have a UTF-8 encoded XML file which is emailed as an attachment. When the email recipient opens the email and saves the attachment, the XML file is no longer UTF-8 (it's instead reporting ANSI encoding). In this instance, the recipient used Microsoft Outlook, if it matters.I have a UTF-8 encoded XML file which is emaile