diff --git a/examples/miniapps/mail_service/container.py b/examples/miniapps/mail_service/container.py
new file mode 100644
index 00000000..5603d320
--- /dev/null
+++ b/examples/miniapps/mail_service/container.py
@@ -0,0 +1,41 @@
+"""Mail service and user registration DI container example."""
+
+from dependency_injector.containers import DeclarativeContainer
+from dependency_injector.providers import Callable, Singleton
+
+import example
+
+
+class Container(DeclarativeContainer):
+    """DI container."""
+
+    mail_service = Singleton(example.MailService,
+                             host='localhost',
+                             port=587,
+                             login='my_login',
+                             password='super_secret_password')
+
+    add_user = Callable(example.add_user,
+                        mailer=mail_service)
+
+
+if __name__ == '__main__':
+    print('Using real mail service:')
+    Container.add_user('sample@mail.com', 'password')
+    # Using real mail service:
+    # Connecting server localhost:587 with my_login:super_secret_password
+    # Sending "Your password is password" to "sample@mail.com"
+
+    print('Using mail service stub:')
+    Container.add_user('sample@mail.com', 'password',
+                       mailer=example.MailServiceStub())
+    # Using mail service stub:
+    # Emulating sending "Your password is password" to "sample@mail.com"
+
+    # Also you can override provider by another provider:
+    Container.mail_service.override(Singleton(example.MailServiceStub))
+    print('Using mail service stub by overriding mail service provider:')
+    Container.add_user('sample@mail.com', 'password')
+    # Using mail service stub by overriding mail service provider:
+    # Emulating sending "Your password is password" to "sample@mail.com"
+    Container.mail_service.reset_override()  # Resetting provider overriding
diff --git a/examples/miniapps/mail_service/example.py b/examples/miniapps/mail_service/example.py
new file mode 100644
index 00000000..ae69b9aa
--- /dev/null
+++ b/examples/miniapps/mail_service/example.py
@@ -0,0 +1,39 @@
+"""Mail service and user registration example."""
+
+
+class AbstractMailService(object):
+    """Abstract mail service."""
+
+    def send(self, email, body):
+        """Send email."""
+        raise NotImplementedError()
+
+
+class MailService(AbstractMailService):
+    """Mail service."""
+
+    def __init__(self, host, port, login, password):
+        """Initializer."""
+        self._host = host
+        self._port = port
+        self._login = login
+        self._password = password
+
+    def send(self, email, body):
+        """Send email."""
+        print('Connecting server {0}:{1} with {2}:{3}'.format(
+            self._host, self._port, self._login, self._password))
+        print('Sending "{0}" to "{1}"'.format(body, email))
+
+
+class MailServiceStub(AbstractMailService):
+    """Mail service stub."""
+
+    def send(self, email, body):
+        """Send email."""
+        print('Emulating sending "{0}" to "{1}"'.format(body, email))
+
+
+def add_user(email, password, mailer):
+    """Register user."""
+    mailer.send(email, 'Your password is {0}'.format(password))