Gabriele Bulfon: > Thanks so much for the deep explanation :) Considering the questions asked, I must keep the conversation at a basic level.
> Kernel is illumos, I exclude it can be a bug in the kernel stack. > I will check Postfix config, but I don't think there is any huge > limit as you suggested. Don't overlook the firewall (yours or theirs). or other boxes in the middle that may manipulate TCP packets. > What about the "PIX workaround"? That causes Postfix to speak SMTP slower. If the data sent over an established TCP connection can trigger a TCP SYN flood, then SOMETHING AT THE NETWORK LEVEL is massively screwed up. Wietse