diff --git a/sdk/eventhub/azure-eventhub/CHANGELOG.md b/sdk/eventhub/azure-eventhub/CHANGELOG.md
index 084e27f55c83..2299941d6cc2 100644
--- a/sdk/eventhub/azure-eventhub/CHANGELOG.md
+++ b/sdk/eventhub/azure-eventhub/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Release History
 
+## 5.6.1 (2021-07-07)
+
+### Fixed
+
+- Fixed a bug for checking that `azure.eventhub.amqp.AmqpMessageHeader` and `azure.eventhub.amqp.AmqpMessageProperties` contain specific properties using the `in` keyword.
+
 ## 5.6.0 (2021-07-07)
 
 ### Features Added
diff --git a/sdk/eventhub/azure-eventhub/azure/eventhub/_mixin.py b/sdk/eventhub/azure-eventhub/azure/eventhub/_mixin.py
index f1db10965826..ff25ea4083d4 100644
--- a/sdk/eventhub/azure-eventhub/azure/eventhub/_mixin.py
+++ b/sdk/eventhub/azure-eventhub/azure/eventhub/_mixin.py
@@ -41,6 +41,10 @@ def __ne__(self, other):
         """Compare objects by comparing all attributes."""
         return not self.__eq__(other)
 
+    def __contains__(self, key):
+        # type: (Any) -> bool
+        return key in self.__dict__
+
     def __str__(self):
         # type: () -> str
         return str({k: v for k, v in self.__dict__.items() if not k.startswith("_")})
diff --git a/sdk/eventhub/azure-eventhub/tests/unittest/test_dict_mixin.py b/sdk/eventhub/azure-eventhub/tests/unittest/test_dict_mixin.py
new file mode 100644
index 000000000000..e43f34c491a0
--- /dev/null
+++ b/sdk/eventhub/azure-eventhub/tests/unittest/test_dict_mixin.py
@@ -0,0 +1,75 @@
+# coding=utf-8
+# ------------------------------------
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+# ------------------------------------
+
+import pytest
+from azure.eventhub._mixin import DictMixin
+
+class TestDictMixin:
+
+    def test_contains_haskey(self):
+        model = DictMixin()
+        key = "testkey"
+        value = "testval"
+        model.__setitem__(key, value)
+        #assert model.__contains__(key)
+        assert key in model
+        assert model.has_key(key)
+
+    def test_getitem_get(self):
+        model = DictMixin()
+        key = "testkey"
+        value = "testval"
+        model.__setitem__(key, value)
+        assert model.__getitem__(key) == "testval"
+        assert model.get(key) == "testval"
+
+    def test_repr_str(self):
+        model = DictMixin()
+        key = "testkey"
+        value = "testval"
+        model.__setitem__(key, value)
+        assert model.__repr__() == "{'testkey': 'testval'}"
+
+    def test_len_delitem(self):
+        model = DictMixin()
+        key = "testkey"
+        value = "testval"
+        model.__setitem__(key, value)
+        assert model.__len__() == 1
+        model.__delitem__(key)
+        assert model[key] is None
+
+    def test_eq_ne(self):
+        model = DictMixin()
+        model2 = DictMixin()
+        key = "testkey"
+        value = "testval"
+        value2 = "testval2"
+        model.__setitem__(key, value)
+        model2.__setitem__(key, value2)
+        assert model.__ne__(model2) is True
+
+    def test_update(self):
+        model = DictMixin()
+        key = "testkey"
+        value = "testval"
+        updatedval = "updatedval"
+        model.__setitem__(key, value)
+        updated = {key: updatedval}
+        model.update(updated)
+        assert model[key] == updatedval
+    
+    def test_values_items(self):
+        model = DictMixin()
+        key = "testkey"
+        value = "testval"
+        key2 = "testkey2"
+        value2 = "testval2"
+        model.__setitem__(key, value)
+        model.__setitem__(key2, value2)
+        vals = model.values()
+        for item in model.items():
+            assert item[1] in vals