I had a heck of a time getting the activation message to come through my e-mail server.  It wasn't being tagged as spam, it was being rejected completely prior to spam checking.

Apparently it didn't like the nobody@vps.jimbutcheronline.com used for the envelope-from address. I think it was the "vps.jimbutcheronline.com" part that caused problems.  That or it didn't like there was no reverse dns ip lookup for the ip address the e-mail comes from.

I finally got my activation through by telling it that "vps.jimbutcheronline.com" was actually a domain running on my own server. A bit of an ugly hack but it worked.

This is the first time in many years of running my own server I had a problem like this so I thought I would give you a heads up. I don't do anything too unusual in my mail server config so there may be other people having the same problem that can't even tell because they don't run their own servers to see the errors.