problem whit inernal smtp

[coccia.stefano]

I have a server in my house ad I have a IP from my ISP, my IP is banned and I have do request to the banlist to take off my IP but he send confirm mail to my ISP that don't accept and I can't send mail from the server (webmail, ecc)...
I can change the smtp to plesk? I want put the smtp of my ISP (the same that I use if I send from outlook)