我没有看到您在 RCPT TO 之后报告的延迟。我运行一个邮件服务器,该服务器记录每次发送的远程 MTA 的成绩单。查看最近向 gmail 地址发送的一些邮件,我发现 gmail 服务器在我的 RCPT TO 之后几乎立即响应了 250 OK。见下文。(电子邮件地址和 IP 匿名以保护无辜者!)。
Tue Jul 23 16:01:52 2013 GMT DNS MX record lookup for gmail.com:
Tue Jul 23 16:01:52 2013 GMT MX1=gmail-smtp-in.l.google.com, MX2=alt1.gmail-smtp-in.l.google.com, MX3=alt2.gmail-smtp-in.l.google.com
Tue Jul 23 16:01:52 2013 GMT Attempting SMTP connection from smtp.myserver.com [x.x.x.x] to gmail-smtp-in.l.google.com [173.194.64.27] on port 25
Tue Jul 23 16:01:52 2013 GMT Delivery id 813435, process id 21352
Tue Jul 23 16:01:52 2013 GMT received from remotehost: 220 mx.google.com ESMTP b5si18818338obh.145 - gsmtp
Tue Jul 23 16:01:52 2013 GMT smtp.myserver.com sent: EHLO smtp.myserver.com
Tue Jul 23 16:01:52 2013 GMT received from remotehost: 250-mx.google.com at your service, [x.x.x.x]
250-SIZE 35882577
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250 PIPELINING
Tue Jul 23 16:01:52 2013 GMT smtp.myserver.com sent: STARTTLS
Tue Jul 23 16:01:52 2013 GMT received from remotehost: 220 2.0.0 Ready to start TLS
Tue Jul 23 16:01:52 2013 GMT starting TLS...
Tue Jul 23 16:01:52 2013 GMT TLS Enabled.
Tue Jul 23 16:01:52 2013 GMT smtp.myserver.com sent: EHLO smtp.myserver.com
Tue Jul 23 16:01:52 2013 GMT received from remotehost: 250-mx.google.com at your service, [x.x.x.x]
250-SIZE 35882577
250-8BITMIME
250-ENHANCEDSTATUSCODES
250 PIPELINING
Tue Jul 23 16:01:52 2013 GMT smtp.myserver.com sent: MAIL FROM: <sender@sender.com>
Tue Jul 23 16:01:52 2013 GMT received from remotehost: 250 2.1.0 OK b5si18818338obh.145 - gsmtp
Tue Jul 23 16:01:52 2013 GMT smtp.myserver.com sent: RCPT TO: <recipient@gmail.com>
Tue Jul 23 16:01:52 2013 GMT received from remotehost: 250 2.1.5 OK b5si18818338obh.145 - gsmtp
Tue Jul 23 16:01:52 2013 GMT smtp.myserver.com sent: DATA
Tue Jul 23 16:01:52 2013 GMT received from remotehost: 354 Go ahead b5si18818338obh.145 - gsmtp
Tue Jul 23 16:01:52 2013 GMT [sending message...] (14871 bytes)
Tue Jul 23 16:01:52 2013 GMT [message sent]
Tue Jul 23 16:01:53 2013 GMT received from remotehost: 250 2.0.0 OK 1374595312 b5si18818338obh.145 - gsmtp