when i click on View/Text Encoding/Unicode its just a one time thing. When I click on another email and then came back to that one, its in Chinese again.

Just a guess, but just about everyone that has ever posted with this sort of issue is dealing with defective encoding on the sending side. Often created by outlook, and often passing trough Yahoo servers, which are also mis-configured for international mail. Good to see their market is really only English speaking countries.

Open the relevant message source (ctrl+U and do a find for

Content-Language: 

and

charset=

There may be none of Content-Language, but charset should always be present in a multipart mime message, it may also be present multiple times, so check for multiples.

Please post back what you find. Once we know what charsets are being used, we might be able to go some way to understanding the why, and perhaps be able to offer options. It is not an exact science. It should be, but there are just to many folk using old character sets out there still, some have been obsolete since the early 1990s.

Hi. I am not the original poster, but my problem is near enough the same. I receive regular emails that often (not always) fail to display the correct characters, particularly for punctuation. If I turn on text encoding autodetect all is well for the email I am trying to read. But the setting always reverts to its default = off, so I have to keep going back. I followed your advice to check the message source for a relevant email, which is a newsletter apparently compiled from several articles by different authors. I found nothing under 'Content-Language:' but several entries under "charset=" There are:

Content-Type: text/plain; charset=utf-8 Content-Type: text/html; charset=utf-8 v=3D"Content-Type" content=3D"text/html charset=3DUTF-8" /> Content-Type: text/plain; charset=utf-8 Content-Type: text/html; charset=utf-8 v=3D"Content-Type" content=3D"text/html charset=3DUTF-8" />