Since Google Wave is being shut down imminently (about a week from now), and Rizzoma currently looks like the most plausible candidate to replace it, I just went through and copied all of the waves that I actually give a damn about to Rizzoma. All of which is fine, but apparently Rizzoma notifies everyone who has editing privileges to a wave when it gets imported -- and in some cases, that's a lot of people.
So my apologies if I wound up spamming you (in some cases several times). I think their policy is probably appropriate, but it hadn't occurred to me when I did the import.
(The import itself seems to have worked adequately, but the jury is out on the process: Aaron tells me that he got one of those emails, and signed in, but couldn't actually access the wave in question. Don't know why yet, but that's the danger of early-beta software...)