[Jaruzel]

Also not the person you were replying to, but in most blocklists are ranges of what are known as dynamic IPs. i.e. those handed out to residential customers. Because most email spam comes from botnets running on peoples personal machines, these ranges are quite sensibly blocked.

If you want to improve your chances of not being blocked when sending email, get a static IP address for your home connection (if your ISP supports that) or host your mailserver on a server instance at a proper hoster.