I don't get mails any longer

On 2014-02-08 I started not getting mails any longer. I have stopped a server before that I thought did not do any mailing functionality.

Symptoms

cat /var/log/mail.err 

delivers

[...]
Feb  8 10:58:00 euve31070 postfix/smtpd[4110]: fatal: no SASL authentication mechanisms
Feb  8 10:58:00 euve31070 postfix/smtpd[4108]: fatal: no SASL authentication mechanisms
Feb  8 10:58:35 euve31070 postfix/smtpd[4119]: fatal: no SASL authentication mechanisms
Feb  8 10:59:36 euve31070 postfix/smtpd[4120]: fatal: no SASL authentication mechanisms
Feb  8 11:00:49 euve31070 postfix/smtpd[4123]: fatal: no SASL authentication mechanisms

I suspect for every incoming mail there is a line.

I cannot send mail via roundcube, it says

SMTP Error (-1): Connection to server failed.