The MIME specifications specify that the proper method for encoding Content-Type and
Content-Disposition parameter values is the method described in
<ulink url="https://tools.ietf.org/html/rfc2231">rfc2231</ulink>. However, it is common for
some older email clients to improperly encode using the method described in
<ulink url="https://tools.ietf.org/html/rfc2047">rfc2047</ulink> instead.
The MIME specifications specify that the proper method for encoding Content-Type and Content-Disposition parameter values is the method described in <ulink url="https://tools.ietf.org/html/rfc2231">rfc2231</ulink>. However, it is common for some older email clients to improperly encode using the method described in <ulink url="https://tools.ietf.org/html/rfc2047">rfc2047</ulink> instead.