PSCP Can Load the Proxy from a PuTTY Session
Save the SSH destination and HTTP proxy in a named PuTTY session, then load that session for PSCP transfers.
PSCP uses PuTTY's connection configuration. Windows Command Prompt does not supply a universal proxy route to every command it starts.
In PuTTY, configure the intended SSH destination under Session. Open Connection → Proxy, select HTTP CONNECT, and enter the proxy hostname, port and required proxy account. Return to Session and save the complete configuration under a name such as Office SSH.
pscp -load "Office SSH" report.csv [email protected]:/incoming/The example copies a local file to the intended SSH server, using the saved proxy route. Replace the destination and account with those configured for the session. PuTTY also supports using a saved session name in place of a hostname.
The HTTP proxy must permit CONNECT to the SSH service's actual port, often 22. A proxy limited to port 443 can reject the transfer before SSH authentication starts.
The proxy account and SSH account are separate. Keep the server's normal host-key verification and SSH authentication settings. If PuTTY itself connects with this session but PSCP does not, confirm that PSCP is loading the same named session under the same Windows user.