Restricting internal distribution list: warning: unknown smtpd restriction: "insiders_only" Hello all, I am trying to restrict some internal distribution lists from abuse as  per http://www.postfix.org/faq.html#internal-list with  postfix-2.3.8-2+b1 on a debian 4.0 box: main.cf: smtpd_restriction_classes = insiders_only insiders_only = check_sender_access hash:/etc/postfix/insiders, reject smtpd_recipient_restrictions    =    hash:/etc/postfix/protected_destinations,    etc... /etc/postfix/insiders: pe@domain OK /etc/postfix/protected_destinations: fzk@domain insiders_only Hashes properly postmapped, reloaded postfix and it work at first,  denying relay for unauthorized senders. But if pe@domain tries, I get an  error: Feb 18 18:50:08 servidor postfix/smtpd[23032]: connect from  localhost.localdomain[127.0.0.1] Feb 18 18:50:15 servidor postfix/smtpd[23032]: 35F0F100E9:  client=localhost.localdomain[127.0.0.1] Feb 18 18:50:19 servidor postfix/cleanup[23035]: 35F0F100E9:  message-id=<98206455855516.73x8k064x5@server.domain> Feb 18 18:50:19 servidor postfix/qmgr[23030]: 35F0F100E9:  from=, size=373, nrcpt=1 (queue active) Feb 18 18:50:19 servidor postfix/smtpd[23040]: connect from  localhost.localdomain[127.0.0.1] Feb 18 18:50:19 servidor postfix/smtpd[23040]: warning: unknown smtpd  restriction: "insiders_only" Feb 18 18:50:19 servidor postfix/smtpd[23040]: NOQUEUE: reject: RCPT  from localhost.localdomain[127.0.0.1]: 451 4.3.5 Server configuration  error; from= to= proto=ESMTP helo= Feb 18 18:50:19 servidor amavis[21842]: (21842-10) (!) mail_via_smtp:  DATA skipped, no valid recips, 1 Feb 18 18:50:19 servidor amavis[21842]: (21842-10) (!) FWD via SMTP:   -> , 451 4.6.0 Failed, id=21842-10, from  MTA([127.0.0.1]:10025): 451 4.3.5 Failed, id=21842-10, from  MTA([127.0.0.1]:10025): 451 4.3.5 Server configuration error Feb 18 18:50:19 servidor postfix/cleanup[23035]: 3F79D100EA:  message-id=<33800836418899.7v33k008bk@server.domain> Feb 18 18:50:19 servidor amavis[21842]: (21842-10) Blocked TEMPFAIL,  [127.0.0.1]  -> , Message-ID:  <98206455855516.73x8k064x5@server.domain>, mail_id: N6J-qB1TBFt3, Hits:  -0.744, 236 ms Feb 18 18:50:19 servidor postfix/smtpd[23040]: disconnect from  localhost.localdomain[127.0.0.1] Feb 18 18:50:19 servidor postfix/qmgr[23030]: 3F79D100EA:  from=, size=889, nrcpt=1 (queue active) Feb 18 18:50:19 servidor postfix/smtp[23036]: 35F0F100E9:  to=, relay=127.0.0.1[127.0.0.1]:10024, delay=5.7,  delays=5.5/0/0/0.24, dsn=4.3.5, status=deferred (host  127.0.0.1[127.0.0.1] said: 451 4.3.5 Failed, id=21842-10, from  MTA([127.0.0.1]:10025): 451 4.3.5 Server configuration error (in reply  to end of DATA command)) I even tried this on master.cf: 127.0.0.1:10025 inet    n -  n  -   -   smtpd    -o content_filter=    -o local_recipient_maps=    -o relay_recipient_maps=    -o smtpd_restriction_classes=    -o smtpd_client_restrictions=    -o smtpd_helo_restrictions=    -o smtpd_sender_restrictions=    -o smtpd_restriction_classes=    -o mynetworks=127.0.0.0/8 I have amavis on port 10024, looks like it is involved on the error, but  I could not establish or perceive the correlation. I use  postfix-2.3.8-2+b1 in a  debian 4.0 box. Thanks in advance for any hint. Regards, --  Marcio Merlone