I have been using this Open Source/ free .Net component to deliver files to SFTP without any issues for the last 2 years.
If you reference the assembly files (Tamir.SharpSSH.dll + 2), in few
lines of code you can do SFTP..
Sftp sftpClient = new Sftp(host, userName, password);
You can develop a windows application or a windows service to deliver fules
Download Assembly Here:
SharpSSH is a pure .NET implementation of the SSH2 client protocol suite. It provides an API for communication with SSH servers and can be integrated into any .NET application.
The library is a C# port of the JSch project from JCraft Inc. and is released under BSD style license.
SharpSSH allows you to read/write data and transfer files over SSH channels using an API similar to JSch's API. In addition, it provides some additional wrapper classes which offer even simpler abstraction for SSH communication.