If I understand you correctly the problem is that the HTMLLayout class does not have a character set part in its content type?

One thing is that characters are unicode internally, but the encoding might very well be single bytes (like ISO-Latin-1) so it is not necessarily so that it is UTF-8.

Can you provide a simple test case showing an incorrectly encoded message?

Surely I do!

import org.apache.log4j.Logger;
import org.apache.log4j.SimpleLayout;
import org.apache.log4j.net.SMTPAppender;

public class testlog {

        private static Logger logger =
        Logger.getLogger("testlog");

        public static void main(String[] args)
        {
                        SMTPAppender appender = new SMTPAppender();
                        appender.setSMTPHost("alt1.gmail-smtp-in.l.google.com");
                        appender.setFrom(args[0]);
                        appender.setName("CHARSETMAIL");
                        appender.setSubject("Encoding FAIL");
                        appender.setTo(args[0]);
                        appender.setLayout(new SimpleLayout() {
                                @Override
                                public String getContentType()
                                {
                                        return "text/plain; charset=\"UTF-8\"";
                                }
                        });
                        appender.activateOptions();
                        logger.addAppender(appender);

                logger.error("Μπορῶ νὰ φάω σπασμένα γυαλιὰ χωρὶς νὰ πάθω τίποτα. \n Ek get etið gler án þess að verða sár. \n Я магу есці шкло, яно мне не шкодзіць.\n\n");
        }

}

Try running it as java -cp .:log4j-1.2.14.jar:mail.jar:activation.jar testlog {whoeveryouare}@gmail.com
With and without the anonymous subclass.

With it, you'll get proper message with greek and cyrillic; without it, you'll get question marks instead of those characters.

Created attachment 22495 [details]
The source file (UTF8)

This file can be used as a test case.

The layout does have the correct values for contentType.  See http://en.wikipedia.org/wiki/MIME for a summary of the various fields of the MIME type (a little easier to read than the IETF RFC's).  The problem is with the SMTPAppender does not properly encode the message into the form specified by the RFC.  Could you try this and see if works for you?  Will have to dig a little deeper to see what to do when a contentType other than "text/plain" is specified.


ndex: src/main/java/org/apache/log4j/net/SMTPAppender.java
===================================================================
--- src/main/java/org/apache/log4j/net/SMTPAppender.java	(revision 686147)
+++ src/main/java/org/apache/log4j/net/SMTPAppender.java	(working copy)
@@ -322,10 +322,15 @@
 	}
       }
       t = layout.getFooter();
-      if(t != null)
-	sbuf.append(t);
-      part.setContent(sbuf.toString(), layout.getContentType());
-
+      if(t != null) {
+	     sbuf.append(t);
+      }
+      String contentType = layout.getContentType();
+      if (contentType == null || contentType.equals("text/plain")) {
+         part.setText(sbuf.toString(), "UTF-8");
+      } else {
+         part.setContent(sbuf.toString(), contentType);
+      }
       Multipart mp = new MimeMultipart();
       mp.addBodyPart(part);
       msg.setContent(mp);

I'll try it tomorrow, but I suppose you should support text/* (notably text/html) the same way.

Committed change in rev 705140 after much experimentation.  JavaMail documentation doesn't see to offer much guidance on creating messages containing non-ascii characters.  

Subjects containing non-ASCII characters were also mangled.