I recently contacted Spotify support about full external management. Best tracks in my playlists are removed externally. Tracks are inserted at old dates. Queue changes often and doesn't play every track once until the end of a shuffled playlist. Spotify determines what is in my playlists and determines what is played. There's more.
I have to record a playlist in order to maintain it (recording entire library isn't doable), while even local data is managed externally.
I contacted Spotify support via icloud email, because that was tied to the account. Those e-mails are now gone from apple servers. I didn't remove any of those e-mails, they're gone.
My SMTP in thunderbird didn't work again, again correlated with sending critical information (such as external management Spotify support emails are gone in icloud.com email). Then CIA/NSA or such disabled saving passwords in my thunderbird. I had to find it in about:config to save passwords in my thunderbird again.