How to troubleshoot email errors when using a VPN:

1. Check for misconfigured or missing settings within the VPN: Check the settings of the VPN, as incorrect or missing settings can prevent emails from being sent or received.


2. Check redirection rules in the remote desktop: In order to send emails from the remote desktop, check whether redirection rules are valid and set up properly.


3. Check the firewall settings: Make sure that the firewall settings are set according to the requirements of the operating system.


4. Check proxy settings: Ensure that the right proxy settings are in place to be able to send and receive emails.


5. Check if port numbers are blocked: Certain network port numbers may be blocked which would prevent emails from being properly sent or received.