> (delivery temporarily suspended: lost connection with
> mail.xyz.ab[22.214.171.124] while receiving the initial server greeting)
> What does lost connection with ... while receiving the initial server
> greeting) means?
> Look at tcpdump output. A common cause for this is the presence of
> a cheap firewall that does not properly implement some TCP features.
> I use freebsd ipfw as a firewall.
There may be MORE THAN ONE firewall in the path.
Now is a good time to do a proper tcpdump measurement. Without data
you're just wasting time.