No, there's no real provision in email for SMTP to be on non-port 25. You can make it listen on something else, but the only thing a remote server is going to d

No, there's no real provision in email for SMTP to be on non-port 25. You can make it listen on something else, but the only thing a remote server is going to do is look up the MX record, and then try opening port 25 on it. Since you'll want a forwarder anyway (many many email servers blacklist anything on a known-ISP IP range (ie, home users)), you might be able to find one that allows you to configure a specific port to forward to, but it'd be non-standard.