according to http://api.rubyonrails.org/classes/ActionMailer/Base.htmldefault_charset - The default charset used for the body and to
encode the subject. Defaults to UTF-8. You can also pick a different
charset from inside a method with charset
.
[](http://api.rubyonrails.org/classes/ActionMailer/Base.html#M001564) ActionMailer::Base.charset = 'big5' have a try!