Try like this :
The server is setted here for GMX. You have to set it for your provider.
blat.exe -server SMTP.GMX.COM -f your_E-mail_address -to Destination_E-mail_adress -s "cc text" -body "body text" -u "Login of your E-mail" -pw "Password of your E-mail"
http://www.blat.net/syntax/syntax.html
And here a list of the most commons SMTP and POP Servers :
http://www.arclab.com/en/amlc/list-of-smtp-and-pop3-servers-mailserver-list.html
Edit :
Apparently you'll need stunnel to provide the Secure Sockets Layer (SSL) as required by GMail.
You can also try with an another provider like GMX who worked for me.
Or you can try Mailsend :
https://github.com/muquit/mailsend/