I am using Fedora 4 for postfix + mysql + dovecot setup
I done the postfix+mysql settings, but there is problem in dovecot settings

my database structure is
-------------+---------+----------+------------------------------------
| username | passwd | domain | uid | gid | maildrop | pppuser |+----------+--------+--------------+-----+------+-------+----------+-------+----
| test | test123 | test.com | 1 | 0 | /var/spool/mail |abhina |+----------+--------+--------------+-----+------+-------+----------+-------+----

i want to fetch mail threw dovecot . for this i did
/etc/dovecot.conf
auth_userdb = mysql /etc/dovecot-mysql.conf
auth_passdb = mysql /etc/dovecot-mysql.conf
first_valid_uid = 500
default_mail_env = mbox:/var/spool/mail/:INDEX=/var/indexes/%u

/etc/dovecot-mysql.conf
db_host = 127.0.0.1
db_port = 3306
db = sendmail
db_user = csdhiman
db_passwd = csdhiman
db_client_flags = 0
default_pass_scheme = PLAIN
password_query = SELECT passwd FROM users WHERE username = '%u'
user_query = SELECT maildrop, 500 AS uid, 500 AS gid FROM users WHERE username = '%u'

I can authenticate my passwords but cannt download mails
Please check for changes ....

I'm not an expert at any of this, but it seems like your database has a UID of "1" and your dovecot settings all say valid UID's need to be 500 or greater.

I got the same problem, were you able to solve your?