也許根據以下的 smtp command 可以用來 check email 名單的正確性
URL: http://www.ip-address.org/verify/email-checker.php Resolving host name "gmail-smtp-in.l.google.com"... Connecting to host address "209.85.225.27"... Connected. S 220 mx.google.com ESMTP m8si9351085icw.142 C HELO ip-address.org S 250 mx.google.com at your service C MAIL FROM: <[email protected]> S 250 2.1.0 OK m8si9351085icw.142 C RCPT TO: <[email protected]> S 250 2.1.5 OK m8si9351085icw.142 C DATA S 354 Go ahead m8si9351085icw.142 This host states that the address is valid. Disconnected.