[Dovecot] Dovecot did not accept Login from Host

[email at randpoger.org]

 Hi!

 My Dovecot is running and i can connect + login through telnet:

 --------------------------------------------
>> telnet localhost 143
 Trying ::1...
 Trying 127.0.0.1...
 Connected to localhost.
 Escape character is '^]'.
 * OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE 
 STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot ready.

>> 1 login user passwort
 1 OK [...] Logged in
 --------------------------------------------


 But through my domain i can only connect, but than i get an error:
 --------------------------------------------
>> telnet domain.de 143
 Trying xx.xxx.xxx.xx...
 Connected to domain.de.
 Escape character is '^]'.
 * OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE 
 STARTTLS AUTH=PLAIN AUTH=LOGIN] Dovecot ready.

>> 1 login user passwort
 1 NO [AUTHENTICATIONFAILED] Authentication failed.
 --------------------------------------------



 My dovecot.conf:

 --------------------------------------------
 protocols = imap imaps
 
 ssl_cert_file = /etc/ssl/certs/dovecot.pem
 ssl_key_file = /etc/ssl/private/dovecot.pem

 mail_location= /var/mail/%u
 
 log_path = /var/log/dovecot.log
 log_timestamp = "%Y-%m-%d %H:%M:%S "

 auth_verbose = yes
 auth_debug = yes
 
 protocol imap {
 }
 auth default {
   mechanisms = plain login
   passdb pam {
   }
   userdb passwd {
   }
   user = root
 }
 --------------------------------------------

 If i try to connect+login through an domain, dovecot write NOTHING into 
 the .log

 Someone ideas about this?