Find Users With Valid Email Addresses

Write a query to find all users who have a valid email address. A valid email has a prefix name and a domain of `@leetcode.com`. The prefix name is a string that starts with a letter and can contain letters (case-insensitive), digits, underscore `'_'`, period `'.'`, and/or dash `'-'`. The prefix name must not contain any other special characters. ### Schema: `Users` | Column Name | Type | | :--- | :--- | | user_id | int | | name | varchar | | mail | varchar | Return the result table in any order.