using postfix to send through a relay server that requires authentication
I'm a nube and i learned that i shouldnt have port 25 opened the hard way, when installing my mail server I left it open, now i have to send all of my websites email through a relay server. I'm using windows to host for now. I wanna switch to linux. but i cant figure out how to send mail through a relay server that requires authentication using postfix. thank you for your help in advance.
ps.. if you have an alternative program that you think i should use instead, then be prepared to help me with that.
so far i tried sendmail and someone told me to use postfix, so i switched to post fix and still can't figure out how to do it