> I'm guessing I could use one of those services (and > software) that lets you use a dynamic IP address (by doing something like > updating you if your IP address changes.
I would not recommend running an MTA on a dynamic IP address. I can absolutely guarantee you that emails sent from such a system will not reach the recipient. Most email servers block emails from MTAs with dynamic IP addresses. When running an MTA, IP address reputation is a huge factor in whether or not your emails land in spam or not. If you want to run your own MTA, you need a static IP that is not on any blocklists.
