The following tags have self-explanatory href. In all cases the subject is

è is not e
in the first exapmple it is the urlencoding of its rfc1342 representation
=?iso-8859-1?Q?=E8?= is not e




If you use the wrong tag on system that don't have iso-8859-1 compatible tables you get unexpected results. I tested on MacOS X and got Netscape working on good and bad, iCab almost ok with good, Internet Explorer setting Ë rather than è. Old browsers apparently send the "good" form literally, but when it arrives the subject is what was meant.