Mail question - Port 25

HI. Sorry if this is a stupid question, I'm a real newbie ;-) I have a suse 8.2 linux box I use to run apache/php/mysql My ISP has blocked port 25 because they say "customers have been abused through this port". I don't really need / want a mail server but what I would like to do is send email from a php program that I am writing. Will I be able to do this? I assume that I will need to have postfix or sendmail running to send mail from php, right? Which is better/more secure, Postfix or sendmail? When I send mail from my email client I use my ISP's smtp server. Regards, Dan Eskildsen