Now I have added a utility to send mail from the Windows Command Prompt. It's called CopyMail, and it's a free download.
Bear in mind that files sent as attachments increase in size by 35% by the time they arrive in the target mailbox. So don't use it to send large files to your friends. Rather use http://www.sendthisfile.com/, which can handle huge files without clogging your mailbox at all.