Postfix 疑難百解收集

目前慢慢會把一些 Postfix 遇到的一些問題，放在這裡

• timed out while receiving the initial server greeting

echo 0 > /proc/sys/net/ipv4/tcp_window_scaling

原因是 If you use postfix running on Linux and If you try to telnet the above host on port 25, the connection is made but the remote mail server doesn't send its 220 message upon connection.
上次遇到這種主機是 Microsoft ESMTP MAIL Service, Version: 6.0

ref http://dbraslavsky.blogspot.com/2007/12/timed-out-while-receiving-initial.html