On 28 Jan 11:26, Francesco Pasqualini wrote: > problem solved (searching the mailing list)
> in the mail server (ubuntu 6.0.6, exim4) I turned off tcp_window_scaling
>
> in /etc/sysctl.conf
>
>
> net/ipv4/tcp_window_scaling=0
If that fixes it it suggests that you're hitting a broken
firewall/router on the way that doesn't pass on TCP/IP window scaling
information and breaks it... OpenBSD didn't used to turn on the options
for that in pf by default, and I can't remember them off the top of my
head, but I suggest fixing the firewalls and routers rather than
patching the problem by disabling window scaling.
