Encrypt.to is a good way to provide (initial) contact with an encrypted email. Just enter the email address of the recipient and if the lookup for a (public) gpg key is successful, you are free to send. There are various service levels from free to enterprise. Quite handy if you have no email client with gpg support or gpg itself around. 
If you need to check that a remote host has a socket open, check following example. This example creates a socket at the HTTP port over your custom network proxy. If the proxy requires authentication, you may override the default Authenticator. Keep in mind that it is only an example!
For the SSH Authentication the gpgsm package is needed, because we need “scdaemon” = smartcard-daemon