said by stolen:
As far as forwarding outbound SMTP via a 3rd party (IE shaw's servers), google "smarthost smtp". It does add a hop outbound, but it's far cheaper than upgrading my service to business and buying a static ip. I'm not running business services on it, just my own personal domain, and this setup has been working since they started blocking outbound port 25.
If you have a hosting service, it may offer this service for you already.
Mail relaying is a common service offered for free with domain hosting - these hosts require you to use Authenticated SMTP or Secure SMTP over ports like 587. Most MUAs can talk to this easily, and MTAs ought to be able to use it as well. These are allowed because they're authenticated - the mail sender has verified themselves to the relay so the email can be traced back to the origin.
A lot of incoming mail servers also block port 25 inbound from dynamic hosts - so Shaw's requirement of static IPs isn't unusual. So your options are to get a business package, or use your hosting service's mail relaying service.