[Dovecot] Can't receive emails

[Chris]

Hello everyone,

I installed postfix and dovecot (imap + pop) on a debian server.
I can send emails via postfix and I could receive emails via dovecot 
before. Yesterday my server got shutdown and restarted and since then, I 
somehow have some problems.
If I send some emails, I don't receive them in /var/vmail/%d/%n/Maildir
But the login works fine (pop and imap).

How can I figure out, why there are no mails comming?

Thank you
Bye, Chris

dovecot --version
1.0.15

dovecot -n
# 1.0.15: /etc/dovecot/dovecot.conf
base_dir: /var/run/dovecot/
log_path: /var/log/dovecot.log
info_log_path: /var/log/dovecot.debug.log
log_timestamp: %Y-%m-%d %H:%M:%S
protocols: imap imaps pop3 pop3s
disable_plaintext_auth: no
login_dir: /var/run/dovecot//login
login_executable(default): /usr/lib/dovecot/imap-login
login_executable(imap): /usr/lib/dovecot/imap-login
login_executable(pop3): /usr/lib/dovecot/pop3-login
login_greeting: Mailserver ready.
first_valid_uid: 5000
last_valid_uid: 5000
mail_privileged_group: mail
mail_location: maildir:/var/vmail/%d/%n/Maildir
mail_debug: yes
mail_executable(default): /usr/lib/dovecot/imap
mail_executable(imap): /usr/lib/dovecot/imap
mail_executable(pop3): /usr/lib/dovecot/pop3
mail_plugin_dir(default): /usr/lib/dovecot/modules/imap
mail_plugin_dir(imap): /usr/lib/dovecot/modules/imap
mail_plugin_dir(pop3): /usr/lib/dovecot/modules/pop3
pop3_uidl_format(default):
pop3_uidl_format(imap):
pop3_uidl_format(pop3): %08Xu%08Xv
auth default:
   mechanisms: plain login
   passdb:
     driver: sql
     args: /etc/dovecot/dovecot-sql.conf
   userdb:
     driver: passwd
   userdb:
     driver: static
     args: uid=5000 gid=5000 home=/var/vmail/%d/%n allow_all_users=yes
   socket:
     type: listen
     client:
       path: /var/spool/postfix/private/auth
       mode: 432
       user: postfix
       group: postfix
     master:
       path: /var/run/dovecot/auth-master
       mode: 384
       user: vmail

driver = mysql
connect = host=localhost dbname=postfix user=MYUSER password=MYPASS
default_pass_scheme = CRYPT
password_query = SELECT username as user, password FROM mailbox WHERE 
username='%u';