Updating the Postfix configuration to use AriticMail as a relay host is easy. For more advanced configuration scenarios, you’ll need to refer to the Postfix documentation.
Some implementations of Postfix only allow passwords to contain letters and numbers, meaning you may need to ensure your AriticMail password is only alphanumeric.
Find your Postfix config file, typically /etc/postfix/main.cf, and add the following:
smtp_sasl_auth_enable = yes smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_sasl_security_options = noanonymous smtp_sasl_tls_security_options = noanonymous smtp_tls_security_level = encrypt header_size_limit = 4096000 relayhost = [mail.ariticmail.com]:25
Now you need to specify your credentials (optionally, use apikey as username and an API Key as password) in the separate file /etc/postfix/sasl_passwd (you’ll likely need to create it):
Next, make sure the file has restricted read and write access only for root, and use the postmap command to update Postfix’s hash tables to use this new file:
$ sudo chmod 600 /etc/postfix/sasl_passwd $ sudo postmap /etc/postfix/sasl_passwd
Finally, restart Postfix:
$ sudo systemctl restart postfix
If you are getting no mechanism available error messages, it generally indicates that you are missing some SASL authentication libraries.
Install the missing module dependency using apt-get (i.e., Debian, Ubuntu):
$ apt-get install libsasl2-modules
Or using a yum (i.e., RedHat, Fedora, CentOS):
$ yum install cyrus-sasl-plain