diff --git a/customerio/__init__.py b/customerio/__init__.py
index ee707cb..f7dda1c 100644
--- a/customerio/__init__.py
+++ b/customerio/__init__.py
@@ -2,5 +2,5 @@
 
 from customerio.client_base import CustomerIOException
 from customerio.track import CustomerIO
-from customerio.api import APIClient, SendEmailRequest, SendPushRequest, SendSMSRequest
+from customerio.api import APIClient, SendEmailRequest, SendPushRequest, SendSMSRequest, SendInboxMessageRequest
 from customerio.regions import Regions
diff --git a/customerio/api.py b/customerio/api.py
index e2ba140..3474fb9 100644
--- a/customerio/api.py
+++ b/customerio/api.py
@@ -34,6 +34,12 @@ def send_sms(self, request):
         resp = self.send_request('POST', self.url + "/v1/send/sms", request)
         return json.loads(resp)
 
+    def send_inbox_message(self, request):
+        if isinstance(request, SendInboxMessageRequest):
+            request = request._to_dict()
+        resp = self.send_request('POST', self.url + "/v1/send/inbox_message", request)
+        return json.loads(resp)
+
     # builds the session.
     def _build_session(self):
         session = super()._build_session()
@@ -219,7 +225,7 @@ def _to_dict(self):
         return data
 
 class SendSMSRequest(object):
-    '''An object with all the options avaiable for triggering a transactional push message'''
+    '''An object with all the options avaiable for triggering a transactional SMS message'''
     def __init__(self,
             transactional_message_id=None,
             to=None,
@@ -264,3 +270,44 @@ def _to_dict(self):
                 data[name] = value
 
         return data
+
+class SendInboxMessageRequest(object):
+    '''An object with all the options avaiable for triggering a transactional inbox message'''
+    def __init__(self,
+            transactional_message_id=None,
+            identifiers=None,
+            disable_message_retention=None,
+            queue_draft=None,
+            message_data=None,
+            send_at=None,
+            language=None,
+        ):
+
+        self.transactional_message_id = transactional_message_id
+        self.identifiers = identifiers
+        self.disable_message_retention = disable_message_retention
+        self.queue_draft = queue_draft
+        self.message_data = message_data
+        self.send_at = send_at
+        self.language = language
+
+    def _to_dict(self):
+        '''Build a request payload from the object'''
+        field_map = dict(
+            # field name is the same as the payload field name
+            transactional_message_id="transactional_message_id",
+            identifiers="identifiers",
+            disable_message_retention="disable_message_retention",
+            queue_draft="queue_draft",
+            message_data="message_data",
+            send_at="send_at",
+            language="language",
+        )
+
+        data = {}
+        for field, name in field_map.items():
+            value = getattr(self, field, None)
+            if value is not None:
+                data[name] = value
+
+        return data
diff --git a/tests/server.py b/tests/server.py
index 5fdf2cc..d815595 100644
--- a/tests/server.py
+++ b/tests/server.py
@@ -14,6 +14,15 @@ def create_ssl_context():
     """Create SSL context for Python 3.12+ compatibility"""
     context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
     context.minimum_version = ssl.TLSVersion.TLSv1_2
+    # Disable hostname and certificate verification for self-signed certs
+    context.check_hostname = False
+    context.verify_mode = ssl.CERT_NONE
+    # Allow weaker ciphers for test compatibility
+    try:
+        context.set_ciphers('DEFAULT@SECLEVEL=1')
+    except ssl.SSLError:
+        # Fall back if the cipher string is not supported
+        pass
     return context
 
 request_counts = dict()
@@ -28,12 +37,16 @@ class Handler(BaseHTTPRequestHandler):
     '''
     def do_DELETE(self):
         self.send_response(200)
+        self.send_header('Content-Length', '0')
         self.end_headers()
 
     def do_POST(self):
+        response_body = bytes("{}", "utf-8")
         self.send_response(200)
+        self.send_header('Content-Type', 'application/json')
+        self.send_header('Content-Length', str(len(response_body)))
         self.end_headers()
-        self.wfile.write(bytes("{}", "utf-8"))
+        self.wfile.write(response_body)
 
     def do_PUT(self):
         global request_counts
@@ -49,6 +62,7 @@ def do_PUT(self):
         if processed > fail_count:
             # return a valid response
             self.send_response(200)
+            self.send_header('Content-Length', '0')
             self.end_headers()
             return
 
diff --git a/tests/test_api.py b/tests/test_api.py
index 2bd7903..ea68a55 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -5,7 +5,7 @@
 import sys
 import unittest
 
-from customerio import APIClient, SendEmailRequest, SendPushRequest, SendSMSRequest, Regions, CustomerIOException
+from customerio import APIClient, SendEmailRequest, SendPushRequest, SendSMSRequest, SendInboxMessageRequest, Regions, CustomerIOException
 from customerio.__version__ import __version__ as ClientVersion
 from tests.server import HTTPSTestCase
 
@@ -111,5 +111,21 @@ def test_send_sms(self):
 
         self.client.send_sms(sms)
 
+    def test_send_inbox_message(self):
+        self.client.http.hooks = dict(response=partial(self._check_request, rq={
+            'method': 'POST',
+            'authorization': "Bearer app_api_key",
+            'content_type': 'application/json',
+            'url_suffix': '/v1/send/inbox_message',
+            'body': {"identifiers": {"id":"customer_1"}, "transactional_message_id": 100}
+        }))
+
+        inbox_message = SendInboxMessageRequest(
+            identifiers={"id":"customer_1"},
+            transactional_message_id=100,
+        )
+
+        self.client.send_inbox_message(inbox_message)
+    
 if __name__ == '__main__':
     unittest.main()