diff --git a/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/InboxManager.java b/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/InboxManager.java
new file mode 100644
index 000000000..908ddec90
--- /dev/null
+++ b/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/InboxManager.java
@@ -0,0 +1,42 @@
+/**
+ *
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.inbox;
+
+import java.util.Map;
+import java.util.WeakHashMap;
+
+import org.jivesoftware.smack.Manager;
+import org.jivesoftware.smack.XMPPConnection;
+
+public final class InboxManager extends Manager {
+
+    public static final String NAMESPACE_1 = "urn:xmpp:inbox:1";
+    private static final Map<XMPPConnection, InboxManager> INSTANCES = new WeakHashMap<>();
+
+    private InboxManager(XMPPConnection connection) {
+        super(connection);
+    }
+
+    public static InboxManager getInstanceFor(XMPPConnection connection) {
+        InboxManager inboxManager = INSTANCES.get(connection);
+        if (inboxManager == null) {
+            inboxManager = new InboxManager(connection);
+            INSTANCES.put(connection, inboxManager);
+        }
+        return inboxManager;
+    }
+}
diff --git a/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/element/EntryElement.java b/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/element/EntryElement.java
new file mode 100644
index 000000000..a978ded6b
--- /dev/null
+++ b/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/element/EntryElement.java
@@ -0,0 +1,73 @@
+/**
+ *
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.inbox.element;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.util.XmlStringBuilder;
+import org.jivesoftware.smackx.inbox.InboxManager;
+
+import org.jxmpp.jid.EntityBareJid;
+
+public class EntryElement implements ExtensionElement {
+
+    public static final String ELEMENT = "entry";
+    public static final String ATTR_UNREAD = "unread";
+    public static final String ATTR_JID = "jid";
+    public static final String ATTR_ID = "id";
+
+    private final int unreadCount;
+    private final EntityBareJid jid;
+    private final String id; // TODO: Legacy Stanza ID, Origin ID, Stanza ID or MAM ID?
+
+    public EntryElement(int unreadCount, EntityBareJid jid, String id) {
+        this.unreadCount = unreadCount;
+        this.jid = jid;
+        this.id = id;
+    }
+
+    public int getUnreadCount() {
+        return unreadCount;
+    }
+
+    public EntityBareJid getJid() {
+        return jid;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    @Override
+    public String getNamespace() {
+        return InboxManager.NAMESPACE_1;
+    }
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public XmlStringBuilder toXML(XmlEnvironment xmlEnvironment) {
+        return new XmlStringBuilder(this)
+                .attribute(ATTR_UNREAD, getUnreadCount())
+                .attribute(ATTR_JID, getJid())
+                .attribute(ATTR_ID, getId())
+                .closeEmptyElement();
+    }
+}
diff --git a/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/element/FinElement.java b/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/element/FinElement.java
new file mode 100644
index 000000000..afa0334c9
--- /dev/null
+++ b/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/element/FinElement.java
@@ -0,0 +1,81 @@
+/**
+ *
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.inbox.element;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.util.XmlStringBuilder;
+import org.jivesoftware.smackx.inbox.InboxManager;
+import org.jivesoftware.smackx.rsm.packet.RSMSet;
+
+public class FinElement implements ExtensionElement {
+
+    public static final String ELEMENT = "fin";
+    public static final String ATTR_TOTAL = "total";
+    public static final String ATTR_UNREAD = "unread";
+    public static final String ATTR_ALL_UNREAD = "all-unread";
+
+    private final int total;
+    private final int unread;
+    private final int allUnread;
+
+    private RSMSet rsmData; // TODO: What is RSM data? RSM set?
+
+    public FinElement(RSMSet rsmData, int total, int unread, int allUnread) {
+        this.rsmData = rsmData;
+        this.total = total;
+        this.unread = unread;
+        this.allUnread = allUnread;
+    }
+
+    public RSMSet getRsmData() {
+        return rsmData;
+    }
+
+    public int getTotal() {
+        return total;
+    }
+
+    public int getUnread() {
+        return unread;
+    }
+
+    public int getAllUnread() {
+        return allUnread;
+    }
+
+    @Override
+    public String getNamespace() {
+        return InboxManager.NAMESPACE_1;
+    }
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public XmlStringBuilder toXML(XmlEnvironment xmlEnvironment) {
+        return new XmlStringBuilder(this)
+                .attribute(ATTR_TOTAL, getTotal())
+                .attribute(ATTR_UNREAD, getUnread())
+                .attribute(ATTR_ALL_UNREAD, getAllUnread())
+                .rightAngleBracket()
+                .optAppend(getRsmData())
+                .closeElement(this);
+    }
+}
diff --git a/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/element/InboxElement.java b/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/element/InboxElement.java
new file mode 100644
index 000000000..3ab3ee44c
--- /dev/null
+++ b/smack-experimental/src/main/java/org/jivesoftware/smackx/inbox/element/InboxElement.java
@@ -0,0 +1,85 @@
+/**
+ *
+ * Copyright 2020 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smackx.inbox.element;
+
+import org.jivesoftware.smack.packet.ExtensionElement;
+import org.jivesoftware.smack.packet.XmlEnvironment;
+import org.jivesoftware.smack.util.XmlStringBuilder;
+import org.jivesoftware.smackx.inbox.InboxManager;
+import org.jivesoftware.smackx.rsm.packet.RSMSet;
+
+public class InboxElement implements ExtensionElement {
+
+    public static final String ELEMENT = "inbox";
+    public static final String ATTR_UNREAD_ONLY = "unread-only";
+    public static final String ATTR_MESSAGES = "messages";
+
+    private final RSMSet filter;
+    private final boolean unreadOnly;
+    private final boolean includeMessages;
+
+    public InboxElement() {
+        this(null);
+    }
+
+    public InboxElement(RSMSet filter) {
+        this(filter, false, true);
+    }
+
+    public InboxElement(RSMSet filter, boolean unreadOnly, boolean includeMessages) {
+        this.filter = filter;
+        this.unreadOnly = unreadOnly;
+        this.includeMessages = includeMessages;
+    }
+
+    public RSMSet getFilter() {
+        return filter;
+    }
+
+    public boolean isUnreadOnly() {
+        return unreadOnly;
+    }
+
+    public boolean isIncludeMessages() {
+        return includeMessages;
+    }
+
+    @Override
+    public String getNamespace() {
+        return InboxManager.NAMESPACE_1;
+    }
+
+    @Override
+    public String getElementName() {
+        return ELEMENT;
+    }
+
+    @Override
+    public XmlStringBuilder toXML(XmlEnvironment xmlEnvironment) {
+        XmlStringBuilder xml = new XmlStringBuilder(this)
+                .optBooleanAttribute(ATTR_UNREAD_ONLY, isUnreadOnly())
+                .optBooleanAttributeDefaultTrue(ATTR_MESSAGES, isIncludeMessages());
+
+        if (getFilter() == null) {
+            return xml.closeEmptyElement();
+        } else {
+            return xml.rightAngleBracket()
+                    .append(getFilter())
+                    .closeElement(this);
+        }
+    }
+}