I was trying to connect to WinSCP from my Web Application using C# however I kept on getting an unknown server error. After doing some research (of which I did not find much), my dear friend helped me out figuring out the solution. So here it goes..
winscp> open "email@example.com:22" -privatekey=C:\keys\private.ppk
Searching for host...
Connecting to host...
Continue connecting to an unknown server and add its host key to a cache?
The server's host key was not found in the cache. You have no guarantee that the server is the computer you think it is.
The server's dss key fingerprint is:
ssh-dss 1024 68:57:83:42:c9:42:08:db:13:0d:80:ec:8b:e2:43:c0
If you trust this host, press Yes. To connect without adding host key to the cache, press No. To abandon the connection press Cancel.
(Y)es, (N)o, C(a)ncel, (C)opy Key: Cancel
Host key wasn't verified!
Host key fingerprint is ssh-dss 1024 68:57:83:42:c9:42:08:db:13:0d:80:ec:8b:e2:43:c0.