Fixed subject header decoding

app/src/main/java/eu/faircode/email/MessageHelper.java

@@ -627,7 +627,16 @@ public class MessageHelper {
 
         subject = MimeUtility.unfold(subject);
 
-        // Fix UTF-8
+        if (subject.contains("=?")) {
+            // Decode header
+            try {
+                subject = MimeUtility.decodeText(subject);
+            } catch (UnsupportedEncodingException ex) {
+                Log.w(ex);
+            }
+            return decodeMime(subject);
+        } else {
+            // Fix UTF-8 plain header
             char[] kars = subject.toCharArray();
             byte[] bytes = new byte[kars.length];
             for (int i = 0; i < kars.length; i++)
@@ -643,6 +652,7 @@ public class MessageHelper {
 
             return decodeMime(subject);
         }
+    }
 
     Long getSize() throws MessagingException {
         long size = imessage.getSize();