Hi, I've a web server running multiple PHP sites. I only need to send emails for subscriptions or other site related stuff. This server doesn't get any incoming mail. I use Postfix on Debian. Now my SMTP port (25) is open. And I get lots of relay attempts. Is it possible to configure postfix for only sending emails? I want to close port 25 and get rid off relay attempts but I'm not sure sending mail will be possible that way.