See also SSMTP

http://www.mechanicalfish.net/classic-blog/posts/92-configuring-postfix-relay-mail-secure-host/

http://www.stefanolocati.it/blog/?p=737

Gmail: http://www.stevemccann.net/2012/12/changing-freepbx-smtp-server-to-gmail.html

From Address: http://www.cyberciti.biz/tips/howto-postfix-masquerade-change-email-mail-address.html

There are various reasons that you may want to configure Postfix to relay all mail to a 'smarthost'.

• Spam filtering
• Port blocking by your ISP
• SPF DNS record doesn't permit your IP to send mail
• Blacklisted IP address
• Etc.

You need a package installed (CentOS, Ubuntu):

yum install cyrus-sasl-plain

apt install libsasl2-modules

You can copy and paste the following into an editor, then adjust the $SMTPHOST and $USERPASS variables for your needs. Then, as root, paste it to the command line:

FILE=/etc/postfix/password
SMTPHOST=your.mailserver.domain
#SMTPHOST=your.mailserver.domain:587
#SMTPHOST=[123.123.123.123]:587
USERPASS=user:pass

# This will overwrite any existing contents
cat << EOF > $FILE
#smtp.isp.com       username:password
$SMTPHOST  $USERPASS
EOF

chown root:root $FILE
chmod 0600 $FILE
postmap hash:$FILE

postconf -e "relayhost = $SMTPHOST"
postconf -e 'smtp_sasl_auth_enable = yes'
postconf -e 'smtp_sasl_password_maps = hash:/etc/postfix/password'
postconf -e 'smtp_sasl_security_options ='

systemctl restart postfix

Additionally, you may be forced to use TLS which may authenticate differently. Here are some additional steps to implement TLS.

Debian/Ubuntu:

apt-get install libsasl2-modules

Redhat/CentOS:

yum install cyrus-sasl-plain cyrus-sasl-ntlm

First we configure the authentication credentials for Postfix.

Newer FreePBX machines create and maintain /etc/postfix/sasl_passwd for you.

Edit /etc/postfix/password to point to a TLS capable host:port:

#smtp.isp.com       username:password
<fqdn_of_mail_svr>:587  <username>:<password>

postmap hash:/etc/postfix/password

Here we enable TLS in Postfix:

postconf -e 'smtp_use_tls=yes'
postfix reload

Envelope-From: http://serverfault.com/questions/533912/how-do-i-change-the-envelope-from-in-postfix

vim /etc/postfix/canonical

This is not a best practice…it's something you might use on a PBX just to get it to send mail.

Append something like this to force all mail to have the specified envelope-from.

# Use the empty regex '//' to map *any* address to the desired envelope sender.
// validsender@yourdomain.tld

postmap /etc/postfix/canonical
postconf -e "canonical_classes = envelope_sender"
postconf -e "canonical_maps = regexp:/etc/postfix/canonical"
postfix reload

Includes SMTP authentication, TLS, envelope-from and trusted CAs

1. Copy to a text editor
2. Edit for your needs
3. Paste into FreePBX Distro CLI as root

This package must be installed on older FreePBX Distro installations:

yum install cyrus-sasl-plain

Copy, edit, then paste in the CLI:

FILE=/etc/postfix/password
# Your valid mail server - colon and port number optional 
SMTPHOST=yoursmtphost.yourdomain.tld:587
# SMTP auth credentials - username may have @
USERPASS=yoursmtpusername:yoursmtpuserpassword
CANONICAL=/etc/postfix/canonical
# Must be a valid authorized sender e-mail address in your domain 
SENDER=validsender@yourdomain.tld
# Trusted CAs aren't configured by default?!
CAFILE=/etc/ssl/certs/ca-bundle.trust.crt

# This will overwrite any existing contents
cat << EOF > $FILE
#smtp.isp.com       username:password
$SMTPHOST  $USERPASS
EOF

chown root:root $FILE
chmod 0600 $FILE
postmap hash:$FILE

postconf -e "relayhost = $SMTPHOST"
postconf -e 'smtp_sasl_auth_enable = yes'
postconf -e 'smtp_sasl_password_maps = hash:/etc/postfix/password'
postconf -e 'smtp_sasl_security_options ='
postconf -e 'smtp_use_tls=yes'

# This will overwrite any existing contents
cat << EOF > $CANONICAL
# Use the empty regex to map *any* address to the desired envelope sender (a valid sender).
// $SENDER
EOF

postmap $CANONICAL
postconf -e "canonical_classes = envelope_sender"
postconf -e "canonical_maps = regexp:$CANONICAL"

# Configure trusted CAs
postconf -e "smtp_tls_CAfile = $CAFILE"

postfix reload