He tenido algunos problemas con el correo que se envía al dominio local rebota y cuando veo la cola de correo, su “aparecer dos errores –
1. Los correos electrónicos que se envían a la “root” – vienen con el mensaje = “user unknown”
2. Los correos electrónicos que se envían a user@domain.com de user2@domain.com – donde domain.com (es el dominio local configurada en el servidor) están subiendo con un message = “mail system configuration error” monitoreando el archivo “maillog”

(mail system configuration error)

X-Postfix; mail system configuration error

y el rebote del correo es el siguiente:

This is the mail system at host smtp.servidorsmtp.com.pe.

####################################################################
# THIS IS A WARNING ONLY.  YOU DO NOT NEED TO RESEND YOUR MESSAGE. #
####################################################################

Your message could not be delivered for more than 4 hour(s).
It will be retried until it is 5 day(s) old.

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.

The mail system

<user@midominio.com.pe> (expanded from <user3@midominio.com.pe>): mail
system configuration error

<user5@midominio.com.pe> (expanded from <user2@midominio.com.pe>): mail
system configuration error

<user7@midominio.com.pe> (expanded from <user2@midominio.com.pe>): mail
system configuration error

<user8@midominio.com.pe> (expanded from <user3@midominio.com.pe>): mail
system configuration error

<user9@midominio.com.pe> (expanded from <user3@midominio.com.pe>):
mail system configuration error

Final-Recipient: rfc822; user2@midominio.com.pe
Original-Recipient: rfc822;user3@midominio.com.pe
Action: delayed
Status: 4.3.5
Diagnostic-Code: X-Postfix; mail system configuration error
Will-Retry-Until: Tue,  5 Apr 2016 11:55:03 -0400 (EDT)

buscar el archivo main.cf
y agregar la línea

…
debug_peer_level = 2
delay_warning_time = 4
disable_vrfy_command = yes
dovecot_destination_recipient_limit = 1
html_directory = no
inet_interfaces = all
local_recipient_maps = virtual_mailbox_maps
mail_owner = postfix
…

posteriormente veremos la solucíon a los errores siguientes

Mar 31 17:09:15 svr amavis[29908]: (29908-01) Open relay? Nonlocal recips but not originating: user1@midominio.com.pe, user2@midominio.com.pe, user3@midominio.com.pe
Mar 31 17:09:15 svr amavis[29908]: (29908-01) (!)connect to /var/run/clamav/clamd.sock failed, attempt #1: Can’t connect to UNIX socket /var/run/clamav/clamd.sock: 111
Mar 31 17:09:15 svr amavis[29908]: (29908-01) ClamAV-clamd: All attempts (1) failed connecting to /var/run/clamav/clamd.sock, retrying (1)
Mar 31 17:09:16 svr amavis[29908]: (29908-01) (!)connect to /var/run/clamav/clamd.sock failed, attempt #1: Can’t connect to UNIX socket /var/run/clamav/clamd.sock: Connection refused
Mar 31 17:09:16 svr amavis[29908]: (29908-01) (!)ClamAV-clamd: All attempts (1) failed connecting to /var/run/clamav/clamd.sock, retrying (2)