[CentOS] Postfix: user unknown

[Manuel Monteiro]

>> Dear all,
>>
>> I have a mail server based on  a CentOS 5.3 machine with postfix.
>>
>>
>> Most of our users are on LDAP (on localhost) but we also have some local
>> users and we are using PAM for authentication.
>
>Are you running nscd on the server? That should smooth out LDAP
>blips, though I would disable nscd's dns caching in /etc/nscd.conf
>
>Is postfix configured to talk directly to LDAP ? What does the
>configuration look like?
>
>nate

We are using nscd with the default configuration.
This server also has a web server, will disabling nscd's dns cache have
negative impact on the performance in this service (or others)?

Postfix does not talk with LDAP. Here's the configuration file:
----------------
queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
mail_owner = postfix
myhostname = mail.astro.up.pt
mydomain = astro.up.pt
myorigin = $mydomain
inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
unknown_local_recipient_reject_code = 550
mynetworks_style = host
virtual_alias_domains = vlti.org sp-astronomia.pt
virtual_alias_maps = hash:/etc/postfix/virtual,
hash:/etc/mailman/virtual-mailman
smtp_generic_maps = hash:/etc/postfix/generic
canonical_maps = hash:/etc/postfix/canonical
alias_maps = hash:/etc/aliases, hash:/etc/mailman/aliases
alias_database = hash:/etc/aliases
recipient_delimiter = +
home_mailbox = Maildir/
mailbox_command = /usr/bin/procmail -d ${USER}
debug_peer_level = 2
debugger_command =
	 PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin
	 xxgdb $daemon_directory/$process_name $process_id & sleep 5
sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop

### AMAVIS
content_filter = smtp-amavis:[localhost]:10024

### SASL
#TLS - SMTP AUTH
disable_vrfy_command = yes
smtpd_use_tls = yes
smtpd_tls_auth_only = yes
tls_random_source = dev:/dev/urandom
smtpd_tls_cert_file = /etc/pki/tls/certs/mail-chained.pem
smtpd_tls_key_file = /etc/pki/tls/private/mail.astro.up.pt.key
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes

# Security
smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks,
reject_unauth_destination

# Options
message_size_limit = 30960000
smtpd_timeout = 600
-----------------------------


Thanks,
Manuel