Using Fiddler on Windows

SmarterMail > Troubleshooting
Fiddler is a useful tool when trying to track down connection and syncing issues between an application installed on a server or desktop and SmarterMail. This tool will capture HTTP(S) traffic on the machine. 

NOTE: This needs to be "Fiddler Classic" - Fiddler anywhere will not work for this. 

  1. Install Fiddler Classic (https://www.telerik.com/download/fiddler) on the machine that is running the application being debugged. (Most likely Outlook or some other email client.) 
  2. Configure it to capture HTTP(S) decrypted traffic. (See https://docs.telerik.com/fiddler/Configure-Fiddler/Tasks/DecryptHTTPS)
  3. Once you have this up and running Start the application in question. ( In this example, Outlook is being used.) 
  4. Replicate the issue that you are seeing: 
    1. If you are having issues with message(s) not downloading, go to the folder you are working with and do a fetch. ( For example, Home -> Update Folder in Outlook.)
    2. Wait for the operation to complete.
    3. If the application has produced any error logs please grab those examples.  (In Outlook this would be the Sync Issues Folder. )
  5. If the issue is intermittent and can not be replicated on demand you can limit the sessions to store and also exclude applications to limit the impact on the end user's machine. 
    1. Hide the browser traffic for example, just right click on it and go to Filter Now. 
    2. and to limit the session go to Keep Sessions in the options bar
  6. Save the capture from Fiddler by clicking File > Save > All Sessions.

Once you have the capture, please Zip it up and send it our way. If it's too big to attach to your reply, you can upload it to SmarterMail's File Storage and send a public link, or we can create an FTP account where you can upload it. 
Article ID: 3724, , Modified: 4/16/2025 at 10:54 AM

Was this article helpful?

Share this article