>Hello.

<snip>

>#sendmail log on linux
>May 22 08:18:18 localhost sendmail[8984]: h4MF9l0B008984: collect: 
>premature EOM: Connection reset
>by mail.netbsd.org

I think this is your clue to your troubles.  You just may be 
encountering the infamous Path MTU Discovery (PMTUD) problem.  (Does 
mail.netbsd.org do PMTUD?)  Do you have this in your sysctl.conf:
net.inet.tcp.mss_ifmtu=1
-- 
Randy

OS X - UNIX for the rest of us
NetBSD - Catch the Power!