diff --git a/pymailtm/pymailtm.py b/pymailtm/pymailtm.py
index 67b4d5e..0fcaed2 100644
--- a/pymailtm/pymailtm.py
+++ b/pymailtm/pymailtm.py
@@ -60,10 +60,23 @@ def get_messages(self, page=1):
                 message_data["intro"],
                 text,
                 html,
+                message_data["seen"],
                 message_data))
 
         return messages
 
+    def mark_seen_message(self, message_id):
+        headers = self.auth_headers
+        headers["Content-Type"] = "application/ld+json";
+
+        r = requests.patch(
+                f"{self.api_address}/messages/{message_id}", headers=headers,
+                          data=json.dumps({'seen': True}))
+        if r.status_code not in [200, 201]:
+            print(r.text)
+            raise CouldNotGetUpdateMessageException(f"HTTP {r.status_code}")
+        return r.json()
+
     def delete_account(self):
         """Try to delete the account. Returns True if it succeeds."""
         r = requests.delete("{}/accounts/{}".format(self.api_address,
@@ -111,6 +124,7 @@ class Message:
     intro: str
     text: str
     html: str
+    seen: bool
     data: Dict
 
     def open_web(self):
@@ -153,6 +167,10 @@ class CouldNotGetMessagesException(Exception):
     """Raised if a GET on /messages returns with a failed status code."""
 
 
+class CouldNotGetUpdateMessageException(Exception):
+    """Raised if a PATCH on /messages returns with a failed status code."""
+
+
 class CouldNotGetAccountException(Exception):
     """Raised if a POST on /accounts or /authorization_token returns with a failed status code."""