I logged into classmates a couple of years ago. I had a message waiting from 2005 from one of my sister's insane ex-friends. That was a blast from the past and hilarious. 18 years without bothering to log in.
Then I realized their business model is so low-rent, they had web 1.0 style protections on scraping all their scanned yearbooks. So I liberated all the ones with anyone I was likely to know and posted them to Archive.org.