Follow these steps to install and configure Postfix to deliver email via SMTP2GO. If you have already installed Postfix, please proceed to Step 4. This document only describes the steps needed to install & configure Postfix to use SMTP2GO. The other settings needed to have a fully functional system are not covered as they vary on a site to site basis.
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
# 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”.
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.
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