Você não definiu ouvintes apropriados para protocolos. Tente começar da configuração de arquivo único assim:
## Dovecot configuration file
mail_location = maildir:/var/mail/%d/%n
protocols = imap pop3
listen = *
mail_uid = mailnull
mail_gid = mail
first_valid_uid = 26
first_valid_gid = 6
last_valid_uid = 0
last_valid_gid = 0
log_path = syslog
syslog_facility = mail
auth_mechanisms = plain
auth_socket_path = /var/run/dovecot/auth-userdb
mail_plugin_dir = /usr/local/lib/dovecot
postmaster_address = postmaster@%d
hostname = %d
sendmail_path = /usr/local/sbin/exim
lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes
passdb {
driver = sql
args = /usr/local/etc/dovecot/dovecot.sql
}
userdb {
driver = sql
args = /usr/local/etc/dovecot/dovecot.sql
}
protocol lda {
}
protocol pop3 {
pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
}
protocol imap {
mail_plugins = quota imap_quota antispam
imap_client_workarounds = delay-newmail tb-extra-mailbox-sep tb-lsub-flags
}
## - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
service auth {
unix_listener auth-userdb {
mode = 0600
user = $mail_uid
group = $mail_gid
}
}
service imap-login {
inet_listener imap {
port = 143
}
inet_listener imaps {
port = 993
ssl = yes
}
}
service pop3-login {
inet_listener pop3 {
port = 110
}
inet_listener pop3s {
port = 995
ssl = yes
}
}
####