Replace From header if incorrectly set

classes/smtp.py

@@ -20,6 +20,8 @@ class SMTP:
     def send_message(self, message, *args, **kwargs):
         if not message.get("From"):
             message["From"] = self.sender
+        elif message["From"] == "None":
+            message.replace_header("From", self.sender)
 
         self.connection.send_message(message, *args, **kwargs)