Postfix sends from localhost using mail but does not relay mails from local clients

Question

For a couple of days I am trying to configure Postfix/Dovecot, I did my best to follow the guides, I can receive mail but cannot send mail from other mail clients than localhost.

Here is a syslog line regarding to a try from a mail-client from the LAN:

Mar 28 12:37:38 mail postfix/smtpd[12524]: NOQUEUE: reject: RCPT from ***.ru[***.***.64.243]: 454 4.7.1 <***@gmail.com>: Relay access denied; from=<***@mymail.server> to=<***@gmail.com> proto=ESMTP helo=<[***.16.98.44]>

Sending mail from the localhost via mail command:

mail ***@gmail.com

This works as expected.

I don't know where to go further, any suggestions/help would be very appreciated.

My main.cf file looks like:

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package     for
# information on enabling SSL in the smtp client.

smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = mail.myserver.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = myserver.com
mydestination = myserver.com, localhost.localdomain, localhost
relayhost = 
mynetworks = 127.0.0.0/8, 5.9.145.38/32
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
home_mailbox = Maildir/
mailbox_command = 
smtpd_sasl_type = dovecot
smtpd_sasl_auth_enable = yes
smtpd_recipient_restrictions =  permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination
smtpd_sasl_path = private/auth

Answer 1

Postfix allows relaying emails from the localhost via mail command because of:

mynetworks = 127.0.0.0/8, 5.9.145.38/32
smtpd_recipient_restrictions = permit_mynetworks

Because your other email-clients are from the LAN, but these LAN IP addresses are not part of mynetworks, postfix prohibits relaying email. You need to add all local IP addresses, you wish to permit sending emails using your mail server as a relay, to mynetworks. I.e. if your LAN is 192.168.1.x you need to add

mynetworks = 127.0.0.0/8, 5.9.145.38/32 192.168.1.0/24

With this configuraion all clients with IP addresses like 192.168.1.x may relay emails using your server.