[thundering herd problem] > The bigger problem is that one or two connections from a > well-connected client will still overwhelm your bandwidth. The real > solution is traffic shaping or QoS to limit the bandwidth used by > SMTP. Your firewall software or your router may already have this > feature, just waiting for configuration.
Many TCP/IP stacks will let you shape traffic. Otherwise, you can set the Postfix tcp_windowsize to a non-zero value to slow down email. I have used a value as low as 512 to keep a low-speed backup connection usable. For this a simple "postfix reload" is not sufficient. For details see: http://www.postfix.org/postconf.5.html#tcp_windowsize Wietse
