My ISP does not provide me with SMTP relaying. If I don't use the email address associated with my account. I have been using a relaying service, they just limit me to 150 (now 450) emails a day. Which seems like a lot, but you run through them fairly quickly when you host an email list with ~25 users. Ah well.
In order to get around the limit, I thought "I'll just send them emails directly, without no realy server". Which I've done, but now I'm reminded why I had to use the relaying the first place, some servers consider me a likely <a href="http://spamblock.outblaze.com/151.203.38.61">spammer</a>. Nuts.
It might be time to move up to static IP. Funny thing is, it used to be _easy_ to get a static IP, now it's more difficult.