This was the .Mac subscription. Poking around the history, it looks like I misunderstood Apple's move at the time. When they discontinued .Mac they also seem to

This was the .Mac subscription. Poking around the history, it looks like I misunderstood Apple's move at the time. When they discontinued .Mac they also seem to have switched to the me.com domain. My impression at the time from whatever messaging they sent out to subscribers was "no more mac.com email" so that's when I switched to Gmail.