Base on Jakob idea propose an implementation for decode.

	But it is clearly not flexible enough:

	  decode [msgno] [part]
	  ? decode 28 2

	Suppose message 28 is a mime with two part, the second part
	will be decoded and sent to stdout.

	* mail/decode.c: First implementation behind Jakobs idea.

@@ -25,6 +25,74 @@
 int
 mail_decode (int argc, char **argv)
 {
-  fprintf (stderr, "Sorry, the decode function hasn't been implemented yet");
+#if 0
+  fprintf (stderr, "Sorry, the decode function hasn't been implemented yet\n");
   return 1;
+#else
+  message_t msg = NULL;
+  int partno;
+  int *list = NULL;
+  int num = util_expand_msglist (argc, argv, &list);
+
+  partno = (num >= 2) ? list[1] : 1;
+
+  if (mailbox_get_message (mbox, list[0], &msg) == 0)
+    {
+      message_t part = NULL;
+      if (message_get_part (msg, partno, &part) == 0)
+	{
+	  body_t body = NULL;
+	  header_t hdr = NULL;
+	  stream_t stream = NULL;
+	  stream_t b_stream = NULL;
+	  size_t len = 0;
+	  char *encoding = NULL;
+
+	  message_get_body (part, &body);
+	  body_get_stream (body, &b_stream);
+	  message_get_header (part, &hdr);
+	  if (header_aget_value (hdr, MU_HEADER_CONTENT_TRANSFER_ENCODING,
+				 &encoding) == 0)
+	    {
+	      size_t lines = 0;
+	      char buffer[512];
+	      off_t off = 0;
+	      size_t n = 0;
+	      FILE *out = ofile;
+	      stream_t d_stream = NULL;
+
+	      message_lines (part, &lines);
+	      if ((util_find_env("crt"))->set && lines > util_getlines ())
+		out = popen (getenv("PAGER"), "w");
+
+	      /* Do I understand this encoding?  */
+	      if (*encoding
+		  && filter_create(&d_stream, b_stream, encoding,
+				   MU_FILTER_DECODE, MU_STREAM_READ) == 0)
+		stream = d_stream;
+	      else
+		stream = b_stream;
+
+	      while (stream_read (stream, buffer, sizeof buffer,
+				  off, &n ) == 0 && n)
+		{
+		  if (ml_got_interrupt())
+		    {
+		      util_error("\nInterrupt");
+		      break;
+		    }
+		  buffer[n] = '\0';
+		  fprintf (out, "%s", buffer);
+		  off += n;
+		}
+	      if (d_stream)
+		stream_destroy (&d_stream, NULL);
+	      if (out != ofile)
+		pclose (out);
+	      free (encoding);
+	    }
+	}
+    }
+  free (list);
+#endif
 }

@@ -60,6 +60,7 @@
 #include <mailutils/iterator.h>
 #include <mailutils/address.h>
 #include <mailutils/mutil.h>
+#include <mailutils/filter.h>
 
 #include <argcv.h>
 #include <getline.h>

@@ -25,7 +25,7 @@ const struct mail_command_entry mail_command_table[] = {
   { "cd",	"cd",	       0, mail_cd,	"cd [directory]" },
   { "ch",	"chdir",       0, mail_cd,	"ch[dir] directory" },
   { "c",	"copy",	       0, mail_copy,	"c[opy] [[msglist] file]" },
-  { "dec",	"decode",      0, mail_decode,	"dec[ode] ???" },
+  { "dec",	"decode",      0, mail_decode,	"dec[ode] [msgno] [part]" },
   { "d",	"delete",      0, mail_delete,	"d[elete] [msglist]" },
   { "di",	"discard",     0, mail_discard,
 			       "di[scard] [header-field...]" },