Email relay

Dear all,
My email server with finished configure SPF, DKIM,... but sometimes go to spam gmail and blacklist by spamhaus.
I want to configure relay email to another mail server to send mail (Email relay service)

How to configure

Open /etc/postfix/main.cf for editing and configure the following;

relayhost = [mail.example.com]:587
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd

Create /etc/postfix/sasl_passwd file and add the authentication details of the external SMTP server:

[mail.example.com]:587 user@example.com:passwd

chmod 0600 /etc/postfix/sasl_passwd
postmap /etc/postfix/sasl_passwd

service postfix restart