Please report any account that tells you that you need to verify your #Mastodon account to continue using it through a private message. It is a scam. We do not require identity verification. Real staff accounts either have a special role badge on their profile or are verified through the joinmastodon.org domain and will typically never reach out through private messages.
This prompts a question... is there some administrative send-to-all toot functionality at the instance level to message all users in cases like this?
If not, it might be worthy of consideration for a future feature.