diff --git a/src/main/java/org/sadtech/bot/core/domain/Mail.java b/src/main/java/org/sadtech/bot/core/domain/Mail.java
index 0f5e67e..779f7d1 100644
--- a/src/main/java/org/sadtech/bot/core/domain/Mail.java
+++ b/src/main/java/org/sadtech/bot/core/domain/Mail.java
@@ -1,5 +1,8 @@
 package org.sadtech.bot.core.domain;
 
+import org.sadtech.bot.core.domain.attachment.Attachment;
+
+import java.util.List;
 import java.util.Objects;
 
 public class Mail extends Content {
@@ -7,6 +10,7 @@ public class Mail extends Content {
     private Integer id;
     private Integer date;
     private String message;
+    private List<Attachment> attachments;
 
     public Mail() {
 
@@ -63,4 +67,12 @@ public class Mail extends Content {
     public int hashCode() {
         return Objects.hash(super.hashCode(), id, date, message);
     }
+
+    public List<Attachment> getAttachments() {
+        return attachments;
+    }
+
+    public void setAttachments(List<Attachment> attachments) {
+        this.attachments = attachments;
+    }
 }
diff --git a/src/main/java/org/sadtech/bot/core/domain/attachment/Attachment.java b/src/main/java/org/sadtech/bot/core/domain/attachment/Attachment.java
new file mode 100644
index 0000000..1c7de29
--- /dev/null
+++ b/src/main/java/org/sadtech/bot/core/domain/attachment/Attachment.java
@@ -0,0 +1,10 @@
+package org.sadtech.bot.core.domain.attachment;
+
+public abstract class Attachment {
+
+    AttachmentType type;
+
+    public AttachmentType getType() {
+        return type;
+    }
+}
diff --git a/src/main/java/org/sadtech/bot/core/domain/attachment/AttachmentType.java b/src/main/java/org/sadtech/bot/core/domain/attachment/AttachmentType.java
new file mode 100644
index 0000000..afce805
--- /dev/null
+++ b/src/main/java/org/sadtech/bot/core/domain/attachment/AttachmentType.java
@@ -0,0 +1,5 @@
+package org.sadtech.bot.core.domain.attachment;
+
+public enum AttachmentType {
+    AUDIO_MESSAGE
+}
diff --git a/src/main/java/org/sadtech/bot/core/domain/attachment/AudioMessage.java b/src/main/java/org/sadtech/bot/core/domain/attachment/AudioMessage.java
new file mode 100644
index 0000000..66151f6
--- /dev/null
+++ b/src/main/java/org/sadtech/bot/core/domain/attachment/AudioMessage.java
@@ -0,0 +1,20 @@
+package org.sadtech.bot.core.domain.attachment;
+
+import java.net.URL;
+
+public class AudioMessage extends Attachment {
+
+    private URL linkOdd;
+
+    public AudioMessage() {
+        type = AttachmentType.AUDIO_MESSAGE;
+    }
+
+    public URL getLinkOdd() {
+        return linkOdd;
+    }
+
+    public void setLinkOdd(URL linkOdd) {
+        this.linkOdd = linkOdd;
+    }
+}
diff --git a/src/main/java/org/sadtech/bot/core/filter/Filter.java b/src/main/java/org/sadtech/bot/core/filter/Filter.java
new file mode 100644
index 0000000..b64ab2e
--- /dev/null
+++ b/src/main/java/org/sadtech/bot/core/filter/Filter.java
@@ -0,0 +1,9 @@
+package org.sadtech.bot.core.filter;
+
+import org.sadtech.bot.core.domain.Content;
+
+public interface Filter<T extends Content> {
+
+    void doFilter(T content);
+
+}