In the logs it's not unusual to see something like this: Jun 16 04:35:12 [firstname.lastname@example.org][126.96.36.199] User (739737: Goosans: <email@example.com>) is being anonymized. Why does firstname.lastname@example.org show up as the session that is deleting email@example.com?
I grepped the logs for December and every one of the logs matched the user deleting and the one getting deleted. I think the above could have happened if the user changed their email address before anonymizing - a likely scenario. Closing this bug.