ximian evolution: 554 SMTP synchronization error

Hello,

I would like to start using evolution as mail client. Recieving mail via
pop3 is no problem but when i try to send an e-mail i get an error-message
saying: "MAIL FROM response error: Interrupted system call". Checking the
log-file "/tmp/camel.log" which i obtained via the command "env
CAMEL_VERBOSE_DEBUG=1 evolution >& /tmp/camel.out" i see it starts with
the following messages:

sending : EHLO hosts (no network card version)
received: 554 SMTP synchronization error
sending : MAIL FROM:<(E-Mail Removed)> received: (null)

After that it starts downloading mail from my pop3 account, without
sending mail. Does anybody has a clou as where the problem may be found? I
use a masquerading and firewalling linux-box between the internet and my
workstation, but i can use kmail with the same settings without a problem.

Thanks in advance,
Rolf Deenen