Configure Simple Relay
To configure the Linux server’s postfix software to relay mail to your SMTP server, open the postfix configuration file for editing:
vim /etc/postfix/main.cf
If your SMTP server allows relay without authentication, simply add the appropriate relayhost entry:
relayhost = exchange.customerdomain.com
Restart the postfix service to apply the settings change:
service postfix reload
Configure Relay with Authentication
Open the postfix configuration file for editing:
vim /etc/postfix/main.cf
If your SMTP server requires authentication (SMTP AUTH) and a secure connection (TLS), use the following procedure (which has been tested with Google Apps and Office365):
relayhost = [smtp.gmail.com]:587 smtp_sasl_auth_enable = yes smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_sasl_security_options = smtp_tls_security_level = may
Create a file where the credentials for SMTP AUTH will be stored:
vim /etc/postfix/sasl_passwd
Enter the credentials:
[smtp.gmail.com]:587 user@domain.com:password
Apply the settings:
postmap /etc/postfix/sasl_passwd chmod 644 /etc/postfix/sasl_passwd service postfix reload
Troubleshooting
Can’t Send Mail from Root
If your mail server requires that mail be sent from a valid address, you may have problems sending mail from the root account, which is required for backup reports and other purposes. In this case, create a mapping for the root user to a valid email address.
Add the following line to /etc/postfix/main.cf:
smtp_generic_maps = hash:/etc/postfix/generic
Add the required email address alias to /etc/postfix/generic:
root user@domain.com
Create the hash file and reload postfix:
postmap /etc/postfix/generic service postfix reload
Vendor-Specific Notes
If you are having trouble sending outbound email with your mail server, you may refer to the hints below, or you may use a mail relay service like SendGrid.
Please follow these instructions to configure postfix to relay via Google Apps or Gmail.
Microsoft Office365
Please follow these instructions to configure Office365 and postfix to work with your Eclipse server.
SendGrid
If you are having trouble with email relay using your mail server, we recommend using SendGrid.