Bitt, I tried a couple of those apps from Tucows, but they just didn't work correctly for me for some reason.

I finally came across a solution, though. I was able to instantly set up a poMMo mailing list site on the web space I'd devoted to this reunion project, and I just finished sending out a mass mailing to 169 people with zero bouncebacks (other than an out of office notification).

I'd first tried Dadamail, but found it too clunky and wouldn't let me add my list of contacts without notifying them that I was adding them (I understand why, but it's still annoying). poMMo has a good UI and lots of options for slowing down the sending of mail, including setting timeouts between sending two emails to the same domain. I erred on the side of caution and chose options that took my 169 emails about 55 minutes. That's perfectly fine with me, as this list won't ever get larger than 500, most likely about 300, so it can take as long as it wants.