[Evolution] Cannot check auth for outgoing mail

[Dennis <dennismail gmx net>]

Hello list,

I am trying to contact a mailserver for ingoing and outgoing mail.
Receiving does work perfectly, but sending is not at all possible: I
tried to check the auth mechanisms that the server offers via the button
in config of evolution, but I get at once a message that the connection
was reset by the server.

What I tried is to get connected to the server via telnet that works
perfectly:

$ telnet  <mailserver-fqdn> 143
Trying <mailserver-ip>...
Connected to <mailserver-fqdn>.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE
IDLE AUTH=PLAIN] Dovecot ready

I can check mails this way, but evolution cannot connect this way to the
server.

Can somebody please help me where to start looking for the cause?

Greets,
Dennis