How should Quoted-Printable Mime-Words be wrapped to the correct line length?
问题 I ran into a bug in a mime parsing library where it blows up on subject lines that contain foreign characters beyond a certain length. It turns out that it would convert the subject into a Quoted-Printable MIME "Encoded-Word" and then try to word-wrap the whole thing to 78 characters. Because MIME-Word encoding has no spaces (they are replaced with underscores) it failed to wrap. Example line being wrapped: Subject: =?UTF-8?Q?lalalla_=E7=84=A1=E6=AD=A4=E7=84=A1=E6=AD=A4=E9=A0=85=E7=9B=AE=AE