Setting up Postfix Smarthost with SMTP2GO

These instructions are for Ubuntu distro. Install Postfix using the following command & follow the instructions (please use the relevant package installation command such as ‘yum’ for other distros):

	# sudo apt-get install postfix		  

Most distros support ‘yum’. You may try the following command to install Postfix:

	# dnf install postfix		  

Make sure Cyrus SASL Library is installed. If it is not installed, you can install it as below using yum or apt-get based on your OS:

	# dnf install cyrus-sasl-plain

(OR)

	# apt-get install libsasl2-modules

Select Internet with smarthost from the General type of mail configuration menu and click ‘Ok’.

Enter mail.smtp2go.com into SMTP relay host and click “Ok”.

Note: If postfix has already been installed and you are reconfiguring with dpkg-reconfigure you will be presented with additional steps. Accept the defaults for any additional steps.

Edit the Postfix configuration file “/etc/postfix/main.cf” using your favorite editor such as vi or jed. Adjust the example below for your needs. Make sure you change the following variables:

your SMTP2GOUsername is your SMTP2GO Username

your SMTP2GOPassword is your SMTP2GO Password

relayhost is [mail.smtp2go.com] followed by :2525.

	# sudo vi /etc/postfix/main.cf

	smtp_sasl_auth_enable = yes
	smtp_sasl_password_maps = static:yourSMTP2GOUsername:yourSMTP2GOPassword
	smtp_sasl_security_options = noanonymous
	smtp_tls_security_level = may
	header_size_limit = 4096000
	relayhost = [mail.smtp2go.com]:2525

	relay_destination_concurrency_limit = 20	  

Note: the last line is important and ensures that your Postfix software doesn’t try to connect with too many concurrent SMTP connections.

Restart the Postfix service:

	# sudo service postfix restart

Note: If you see an error ‘550 unable to verify sender address’ when trying to send an email after setting up, this means your ‘From’ email address doesn’t have a valid MX record setup yet. All emails must be sent from an email address that has an MX record at its domain name.