diff --git a/README.md b/README.md
index a15d65e..b5579e6 100644
--- a/README.md
+++ b/README.md
@@ -75,6 +75,11 @@ specifying a custom formatter class:
             <expectJson>true</expectJson>
             <!-- optional -->
             <includeMethodAndLineNumber>true</includeMethodAndLineNumber>
+            <!-- Mark every message with these additional properties.-->
+            <extraProperties>
+              serverId=SERVER-ID
+              domain=www.domain.com
+            </extraProperties>
         </formatter>
     </appender>
     <root level="debug">
diff --git a/pom.xml b/pom.xml
index 7cd9733..95e7f66 100644
--- a/pom.xml
+++ b/pom.xml
@@ -63,16 +63,12 @@
 			<groupId>ch.qos.logback</groupId>
 			<artifactId>logback-classic</artifactId>
 			<version>1.1.7</version>
+      <scope>provided</scope>
 		</dependency>
 		<dependency>
 			<groupId>org.apache.kafka</groupId>
 			<artifactId>kafka-clients</artifactId>
 			<version>0.10.0.0</version>
 		</dependency>
-		<dependency>
-			<artifactId>slf4j-api</artifactId>
-			<groupId>org.slf4j</groupId>
-			<version>1.7.5</version>
-		</dependency>
 	</dependencies>
 </project>
\ No newline at end of file
diff --git a/src/main/java/com/github/ptgoetz/logback/kafka/KafkaAppender.java b/src/main/java/com/github/ptgoetz/logback/kafka/KafkaAppender.java
index 895be80..72e084d 100644
--- a/src/main/java/com/github/ptgoetz/logback/kafka/KafkaAppender.java
+++ b/src/main/java/com/github/ptgoetz/logback/kafka/KafkaAppender.java
@@ -34,7 +34,7 @@ public void start() {
       exception.printStackTrace();
       throw new RuntimeException("KafkaAppender: Exception initializing Producer.",exception);
     }
-    System.out.println("KafkaAppender: Producer intitialized: "+ producer);
+    System.out.println("KafkaAppender: Producer initialized: "+ producer);
     if (topic == null) {
       LOGGER.error("KafkaAppender requires a topic. Add this to the appender configuration.");
       System.out.println("KafkaAppender requires a topic. Add this to the appender configuration.");
diff --git a/src/main/java/com/github/ptgoetz/logback/kafka/formatter/JsonFormatter.java b/src/main/java/com/github/ptgoetz/logback/kafka/formatter/JsonFormatter.java
index 3ed600f..c3c4243 100644
--- a/src/main/java/com/github/ptgoetz/logback/kafka/formatter/JsonFormatter.java
+++ b/src/main/java/com/github/ptgoetz/logback/kafka/formatter/JsonFormatter.java
@@ -2,14 +2,19 @@
 
 import ch.qos.logback.classic.spi.ILoggingEvent;
 
+import java.io.IOException;
+import java.io.StringReader;
+import java.util.Enumeration;
+import java.util.Properties;
+
 public class JsonFormatter implements Formatter {
-  private static final String QUOTE = "\"";
-  private static final String COLON = ":";
-  private static final String COMMA = ",";
+  private static final char QUOTE = '"';
+  private static final char COLON = ':';
+  private static final char COMMA = ',';
 
   private boolean expectJson = false;
   private boolean includeMethodAndLineNumber = false;
-  private String serverId = null;
+  private String extraProperties = null;
 
   public String format(ILoggingEvent event) {
     StringBuilder sb = new StringBuilder();
@@ -42,10 +47,8 @@ public String format(ILoggingEvent event) {
         quote(stackTraceElement.getLineNumber() + "", sb);
       }
     }
-    if(serverId!=null){
-      sb.append(COMMA);
-      fieldName("serverId", sb);
-      quote(serverId,sb);
+    if(this.extraProperties!=null){
+      sb.append(this.extraProperties);
     }
     sb.append("}");
     return sb.toString();
@@ -78,11 +81,26 @@ public void setIncludeMethodAndLineNumber(boolean includeMethodAndLineNumber) {
     this.includeMethodAndLineNumber = includeMethodAndLineNumber;
   }
 
-  public String getServerId() {
-    return serverId;
+  public String getExtraProperties() {
+    return extraProperties;
   }
 
-  public void setServerId(String serverId) {
-    this.serverId = serverId;
+  public void setExtraProperties(String thatExtraProperties) {
+    final Properties properties = new Properties();
+    try {
+      properties.load(new StringReader(thatExtraProperties));
+    } catch (IOException e) {
+      e.printStackTrace();
+    }
+    Enumeration<?> enumeration = properties.propertyNames();
+    StringBuilder sb = new StringBuilder();
+    while(enumeration.hasMoreElements()){
+      String name = (String)enumeration.nextElement();
+      String value = properties.getProperty(name);
+      sb.append(COMMA);
+      fieldName(name, sb);
+      quote(value,sb);
+    }
+    this.extraProperties = sb.toString();
   }
 }
\ No newline at end of file
diff --git a/src/test/java/com/github/ptgoetz/logback/kafka/formatter/JsonFormatterTest.java b/src/test/java/com/github/ptgoetz/logback/kafka/formatter/JsonFormatterTest.java
index 26b2e9d..1bc8c67 100644
--- a/src/test/java/com/github/ptgoetz/logback/kafka/formatter/JsonFormatterTest.java
+++ b/src/test/java/com/github/ptgoetz/logback/kafka/formatter/JsonFormatterTest.java
@@ -10,19 +10,27 @@ public class JsonFormatterTest extends TestCase {
     @Test
     public void testJsonFormat() {
         String nonJsonMessage = "{\"level\":\"INFO\",\"logger\":\"test\",\"timestamp\":1370918376296,\"message\":\"foobar\"}";
-        String jsonMessage = "{\"level\":\"INFO\",\"logger\":\"test\",\"timestamp\":1370918376296,\"message\":{\"foo\":\"bar\"}}";
+      String jsonMessage =    "{\"level\":\"INFO\",\"logger\":\"test\",\"timestamp\":1370918376296,\"message\":{\"foo\":\"bar\"}}";
+      String nonJsonMessageWithGroupProperties =    "{\"level\":\"INFO\",\"logger\":\"test\",\"timestamp\":1370918376296,\"message\":\"foobar\",\"name2\":\"value2\",\"name1\":\"value1\"}";
 
-        // non-JSON
-        MockLoggingEvent event = new MockLoggingEvent(false);
-        JsonFormatter formatter = new JsonFormatter();
-        formatter.setExpectJson(false);
-        String json = formatter.format(event);
-        assertEquals(nonJsonMessage, json);
+      // non-JSON
+      MockLoggingEvent event = new MockLoggingEvent(false);
+      JsonFormatter formatter = new JsonFormatter();
+      formatter.setExpectJson(false);
+      String json = formatter.format(event);
+      assertEquals(nonJsonMessage, json);
 
-        // JSON
-        event = new MockLoggingEvent(true);
-        formatter.setExpectJson(true);
-        json = formatter.format(event);
-        assertEquals(jsonMessage, json);
+      // JSON
+      event = new MockLoggingEvent(true);
+      formatter.setExpectJson(true);
+      json = formatter.format(event);
+      assertEquals(jsonMessage, json);
+
+      // Group Properties
+      event = new MockLoggingEvent(false);
+      formatter.setExpectJson(false);
+      formatter.setGroupProperties("name1=value1\nname2=value2");
+      json = formatter.format(event);
+      assertEquals(nonJsonMessageWithGroupProperties, json);
     }
 }