Seem to have found a error in version 1.2.6 regarding usernames having a number as the first character. Customers with a number as the first character in thier user name can not login via pop3 clients. However they can login through our webmail interface. If we remove the number from the username then the customer can login.
# 1.2.6: /etc/dovecot.conf # OS: Linux 2.6.31.12-desktop-3mnb x86_64 Mandriva Linux 2010.0 protocols: pop3 ssl_listen: * ssl_cert_file: /etc/pki/tls/certs/dovecot.pem ssl_key_file: /etc/pki/tls/private/dovecot.pem disable_plaintext_auth: no login_dir: /var/run/dovecot/login login_executable: /usr/lib64/dovecot/pop3-login mail_privileged_group: mail mail_location: mbox:~/mail:INBOX=/home/mail/%u mail_executable: /usr/lib64/dovecot/pop3 mail_plugin_dir: /usr/lib64/dovecot/modules/pop3 pop3_uidl_format: %08Xv%08Xu lda: postmaster_address: postmaster@example.com auth default: mechanisms: plain login verbose: yes passdb: driver: pam userdb: driver: passwd socket: type: listen client: path: /var/spool/postfix/private/auth mode: 432 user: postfix group: postfix plugin: quota_warning: storage=95%% /usr/local/bin/quota-warning.sh 95 quota_warning2: storage=80%% /usr/local/bin/quota-warning.sh 80