opensmtpd updates not in OPENBSD_6_6 branch?

Hello all. I am running a OpenBSD 6.6 that I installed late last year. I was recently trying to make sure I'd updated my smtpd to 6.6.4, based on earlier security announcement. As I'm running on a sparc64, syspatch doesn't work. While I'd love to talk about rectifying that, that's a bigger issue.

For now, I figured I would get the -stable branch (OPENBSD_6_6) and that would have an updated smtpd I could install. But, I find that that branch only have smtpd 6.6.0 in it. I was of the impression that was the stable branch, and as such it should get updates, especially including security updates.

Let me know how I should track important updates for my system, without syspatch support for my arch.

Thank you.

- Chris