diff --git a/README.md b/README.md
index 40f07a40..9949b1ab 100644
--- a/README.md
+++ b/README.md
@@ -35,6 +35,7 @@ The subproject `as2-demo-webapp` is licensed under the Apache 2 license.
     * Added support for deprecated signing algorithms `rsa-md5` and `rsa-sha1`
     * Updated to new Mendelson test certificates (key3 and key4 - see http://mendelson-e-c.com/node/3211)
     * The `Content-Transfer-Encoding` value `base64` now works correctly (see [#71](https://github.com/phax/as2-lib/pull/71))
+    * Added a custom `IMICMatchingHandler` interface to `AS2SenderModule` and `AS2MDNReceiverHandler` (see [#59](https://github.com/phax/as2-lib/pull/59))
     * Updated to ph-commons 9.3.4
 * v4.3.0 - 2019-05-17
     * Moved interface `IRefreshablePartnershipFactory` from project as2-server to this project
diff --git a/as2-lib/src/main/java/com/helger/as2lib/crypto/IMICMatchingHandler.java b/as2-lib/src/main/java/com/helger/as2lib/crypto/IMICMatchingHandler.java
new file mode 100644
index 00000000..fed8e11f
--- /dev/null
+++ b/as2-lib/src/main/java/com/helger/as2lib/crypto/IMICMatchingHandler.java
@@ -0,0 +1,46 @@
+package com.helger.as2lib.crypto;
+
+import java.io.Serializable;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+import com.helger.as2lib.exception.OpenAS2Exception;
+import com.helger.as2lib.message.IMessage;
+
+/**
+ * A special handler if MIC is not matched.
+ *
+ * @author Philip Helger
+ * @since 4.4.0
+ */
+public interface IMICMatchingHandler extends Serializable
+{
+  /**
+   * Invoked upon MIC match
+   *
+   * @param aMsg
+   *        The message it is all about. Never null
+   * @param sMIC
+   *        The MIC calculated and received. May not be <code>null</code>.
+   * @throws OpenAS2Exception
+   *         In case of error
+   */
+  void onMICMatch (@Nonnull IMessage aMsg, @Nonnull String sMIC) throws OpenAS2Exception;
+
+  /**
+   * Invoked upon MIC mismatch
+   *
+   * @param aMsg
+   *        The message it is all about. Never null
+   * @param sOriginalMIC
+   *        The MIC calculated here. May be <code>null</code>.
+   * @param sReceivedMIC
+   *        The MIC received from the other side. May be <code>null</code>.
+   * @throws OpenAS2Exception
+   *         In case of error
+   */
+  void onMICMismatch (@Nonnull IMessage aMsg,
+                      @Nullable String sOriginalMIC,
+                      @Nullable String sReceivedMIC) throws OpenAS2Exception;
+}
diff --git a/as2-lib/src/main/java/com/helger/as2lib/crypto/LoggingMICMatchingHandler.java b/as2-lib/src/main/java/com/helger/as2lib/crypto/LoggingMICMatchingHandler.java
new file mode 100644
index 00000000..12e614d8
--- /dev/null
+++ b/as2-lib/src/main/java/com/helger/as2lib/crypto/LoggingMICMatchingHandler.java
@@ -0,0 +1,35 @@
+package com.helger.as2lib.crypto;
+
+import javax.annotation.Nonnull;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.helger.as2lib.message.IMessage;
+
+/**
+ * Logging implementation of {@link IMICMatchingHandler}
+ *
+ * @author Philip Helger
+ * @since 4.40
+ */
+public class LoggingMICMatchingHandler implements IMICMatchingHandler
+{
+  private static final Logger LOGGER = LoggerFactory.getLogger (LoggingMICMatchingHandler.class);
+
+  public void onMICMatch (@Nonnull final IMessage aMsg, @Nonnull final String sMIC)
+  {
+    if (LOGGER.isInfoEnabled ())
+      LOGGER.info ("MIC is matched, MIC: " + sMIC + aMsg.getLoggingText ());
+  }
+
+  public void onMICMismatch (final IMessage aMsg, final String sOriginalMIC, final String sReceivedMIC)
+  {
+    if (LOGGER.isInfoEnabled ())
+      LOGGER.info ("MIC IS NOT MATCHED; original MIC: " +
+                   sOriginalMIC +
+                   " received MIC: " +
+                   sReceivedMIC +
+                   aMsg.getLoggingText ());
+  }
+}
diff --git a/as2-lib/src/main/java/com/helger/as2lib/processor/receiver/net/AS2MDNReceiverHandler.java b/as2-lib/src/main/java/com/helger/as2lib/processor/receiver/net/AS2MDNReceiverHandler.java
index e1e9a158..f49bccd3 100644
--- a/as2-lib/src/main/java/com/helger/as2lib/processor/receiver/net/AS2MDNReceiverHandler.java
+++ b/as2-lib/src/main/java/com/helger/as2lib/processor/receiver/net/AS2MDNReceiverHandler.java
@@ -49,6 +49,8 @@
 
 import com.helger.as2lib.cert.ECertificatePartnershipType;
 import com.helger.as2lib.cert.ICertificateFactory;
+import com.helger.as2lib.crypto.IMICMatchingHandler;
+import com.helger.as2lib.crypto.LoggingMICMatchingHandler;
 import com.helger.as2lib.crypto.MIC;
 import com.helger.as2lib.disposition.DispositionException;
 import com.helger.as2lib.disposition.DispositionType;
@@ -90,6 +92,7 @@ public class AS2MDNReceiverHandler extends AbstractReceiverHandler
   private static final Logger LOGGER = LoggerFactory.getLogger (AS2MDNReceiverHandler.class);
 
   private final AS2MDNReceiverModule m_aModule;
+  private IMICMatchingHandler m_aMICMatchingHandler = new LoggingMICMatchingHandler ();
 
   public AS2MDNReceiverHandler (@Nonnull final AS2MDNReceiverModule aModule)
   {
@@ -97,11 +100,34 @@ public AS2MDNReceiverHandler (@Nonnull final AS2MDNReceiverModule aModule)
   }
 
   @Nonnull
-  public AS2MDNReceiverModule getModule ()
+  public final AS2MDNReceiverModule getModule ()
   {
     return m_aModule;
   }
 
+  /**
+   * @return The current MIC matching handler. Never <code>null</code>.
+   * @since 4.4.0
+   */
+  @Nonnull
+  public final IMICMatchingHandler getMICMatchingHandler ()
+  {
+    return m_aMICMatchingHandler;
+  }
+
+  /**
+   * Set the MIC matching handler to used.
+   *
+   * @param aMICMatchingHandler
+   *        The new handler. May not be <code>null</code>.
+   * @since 4.4.0
+   */
+  public final void setMICMatchingHandler (@Nonnull final IMICMatchingHandler aMICMatchingHandler)
+  {
+    ValueEnforcer.notNull (aMICMatchingHandler, "MICMatchingHandler");
+    m_aMICMatchingHandler = aMICMatchingHandler;
+  }
+
   public void handle (@Nonnull final AbstractActiveNetModule aOwner, @Nonnull final Socket aSocket)
   {
     final String sClientInfo = getClientInfo (aSocket);
@@ -273,8 +299,10 @@ protected final void receiveMDN (@Nonnull final AS2Message aMsg,
    * @param aMsg
    *        Message
    * @return true if mdn processed
+   * @throws OpenAS2Exception
+   *         In case of error; e.g. MIC mismatch
    */
-  public boolean checkAsyncMDN (final AS2Message aMsg)
+  public boolean checkAsyncMDN (@Nonnull final AS2Message aMsg) throws OpenAS2Exception
   {
     try
     {
@@ -315,18 +343,13 @@ public boolean checkAsyncMDN (final AS2Message aMsg)
 
       if (aOriginalMIC == null || aReturnMIC == null || !aReturnMIC.equals (aOriginalMIC))
       {
-        if (LOGGER.isInfoEnabled ())
-          LOGGER.info ("MIC IS NOT MATCHED, original mic: " +
-                       sOriginalMIC +
-                       " return mic: " +
-                       sReturnMIC +
-                       aMsg.getLoggingText ());
+        m_aMICMatchingHandler.onMICMismatch (aMsg, sOriginalMIC, sReturnMIC);
         return false;
       }
 
+      m_aMICMatchingHandler.onMICMatch (aMsg, sReturnMIC);
+
       // delete the pendinginfo & pending file if mic is matched
-      if (LOGGER.isInfoEnabled ())
-        LOGGER.info ("mic is matched, mic: " + sReturnMIC + aMsg.getLoggingText ());
 
       final File aPendingInfoFile = new File (sPendingInfoFile);
       if (LOGGER.isInfoEnabled ())
diff --git a/as2-lib/src/main/java/com/helger/as2lib/processor/sender/AS2SenderModule.java b/as2-lib/src/main/java/com/helger/as2lib/processor/sender/AS2SenderModule.java
index 433cc487..f3f6b0ca 100644
--- a/as2-lib/src/main/java/com/helger/as2lib/processor/sender/AS2SenderModule.java
+++ b/as2-lib/src/main/java/com/helger/as2lib/processor/sender/AS2SenderModule.java
@@ -57,6 +57,8 @@
 import com.helger.as2lib.crypto.ECompressionType;
 import com.helger.as2lib.crypto.ECryptoAlgorithmCrypt;
 import com.helger.as2lib.crypto.ECryptoAlgorithmSign;
+import com.helger.as2lib.crypto.IMICMatchingHandler;
+import com.helger.as2lib.crypto.LoggingMICMatchingHandler;
 import com.helger.as2lib.crypto.MIC;
 import com.helger.as2lib.disposition.DispositionException;
 import com.helger.as2lib.disposition.DispositionType;
@@ -111,9 +113,34 @@ public class AS2SenderModule extends AbstractHttpSenderModule
   private static final String ATTR_PENDINGMDN = "pendingmdn";
   private static final Logger LOGGER = LoggerFactory.getLogger (AS2SenderModule.class);
 
+  private IMICMatchingHandler m_aMICMatchingHandler = new LoggingMICMatchingHandler ();
+
   public AS2SenderModule ()
   {}
 
+  /**
+   * @return The current MIC matching handler. Never <code>null</code>.
+   * @since 4.4.0
+   */
+  @Nonnull
+  public final IMICMatchingHandler getMICMatchingHandler ()
+  {
+    return m_aMICMatchingHandler;
+  }
+
+  /**
+   * Set the MIC matching handler to used.
+   *
+   * @param aMICMatchingHandler
+   *        The new handler. May not be <code>null</code>.
+   * @since 4.4.0
+   */
+  public final void setMICMatchingHandler (@Nonnull final IMICMatchingHandler aMICMatchingHandler)
+  {
+    ValueEnforcer.notNull (aMICMatchingHandler, "MICMatchingHandler");
+    m_aMICMatchingHandler = aMICMatchingHandler;
+  }
+
   public boolean canHandle (@Nonnull final String sAction,
                             @Nonnull final IMessage aMsg,
                             @Nullable final Map <String, Object> aOptions)
@@ -682,20 +709,13 @@ protected void receiveSyncMDN (@Nonnull final AS2Message aMsg,
       if (aOriginalMIC == null || aReturnMIC == null || !aReturnMIC.equals (aOriginalMIC))
       {
         // file was sent completely but the returned mic was not matched,
-        // don't know it needs or needs not to be resent ? it's depended on
-        // what! anyway, just log the warning message here.
-        if (LOGGER.isInfoEnabled ())
-          LOGGER.info ("MIC IS NOT MATCHED, original mic: '" +
-                       aOriginalMIC.getAsAS2String () +
-                       "' return mic: '" +
-                       sReturnMIC +
-                       "'" +
-                       aMsg.getLoggingText ());
+        m_aMICMatchingHandler.onMICMismatch (aMsg,
+                                             aOriginalMIC == null ? null : aOriginalMIC.getAsAS2String (),
+                                             sReturnMIC);
       }
       else
       {
-        if (LOGGER.isInfoEnabled ())
-          LOGGER.info ("MIC is matched, MIC: " + sReturnMIC + aMsg.getLoggingText ());
+        m_aMICMatchingHandler.onMICMatch (aMsg, sReturnMIC);
       }
 
       try