i did #nail -f /var/spool/mail/root and i got the following: ....................................................................................................................................... mailx version nail 11.4 8/29/04. Type ? for help. "/var/spool/mail/root": 10 messages 8 unread. 0 1 MAILER-DAEMON@linu Mon Oct 24 18:49 66/1976 Undelivered Mail Returned to Sender 0 2 MAILER-DAEMON@linu Mon Oct 24 19:02 66/1976 Undelivered Mail Returned to Sender U 3 MAILER-DAEMON@linu Mon Oct 24 19:02 66/1975 Undelivered Mail Returned to Sender U 4 MAILER-DAEMON@linu Mon Oct 25 17:51 66/1975 Undelivered Mail Returned to Sender U 5 MAILER-DAEMON@linu Mon Oct 25 17:52 66/1975 Undelivered Mail Returned to Sender U 6 MAILER-DAEMON@linu Mon Oct 26 13:39 66/1975 Undelivered Mail Returned to Sender U 7 MAILER-DAEMON@linu Mon Oct 26 10:06 66/1935 Undelivered Mail Returned to Sender U 8 MAILER-DAEMON@linu Mon Oct 31 16:36 66/2138 Undelivered Mail Returned to Sender U 9 MAILER-DAEMON@linu Mon Oct 31 16:36 66/2138 Undelivered Mail Returned to Sender U 10 MAILER-DAEMON@linu Mon Oct 31 16:36 66/1975 Undelivered Mail Returned to Sender I am sorry to inform that your message could not be delivered to one or more recipients. It´s attacjed below. for further assistance please send mail to <postmaster> If you do so please include this problem report. You can delete your own text from the attached returned message. admisnistrator@linux.site : unknown user: administrator Final-Recipient: rfc822: Administrator@linux.site Action: failed Status: 5.0.0 Diagnostic Code: X-Postfix: unknown user: "Administrator" ................................................... so it seems there the user administrator@linux.site has not been created I supposed it must be created at any of the tables (canonical, virtual, etc) that postfix requires for mapping what table should I use?? Regards.-