1. 语法验证Checks if the email address follows RFC standards and proper formatting rules.

2. 域名验证Verifies that the domain exists and has valid MX (Mail Exchange) records configured.

3. SMTP 连接测试Connects to the mail server to verify if the specific mailbox exists and can receive emails.

4. 一次性邮箱检测Checks against databases of known temporary email providers and disposable domains.

5. 风险评估Analyzes various factors to determine the overall quality and risk level of the email address.