It depends how you use your SMTP services. Mail is relayed between mail servers on port 25 only. If you wish to receive email from the big wide net then the other SMTP servers look up your MX record for your domain and connect to port 25 on that address. If you are only using it yourself, then that's certainly doable, as you're in control of what ports YOU use. Also relevant when you're using SMTP over TLS etc, which does run on different ports, but other SMTP relays out there won't do that by default, and you clearly have no control over them.
There arwe services out there that will be your mail relay and forward on to you on non-standard ports, but none I'm familiar with. Here's an example -
http://www.no-ip.com/support/guides/...d_port_25.html $40 a year for that.... Is it worth it?
Generally there is a pretty minimal benefit in running your own email services. If your home connection ever goes down, you're not going to receive mail etc, I'd generally advise against it anyway.
