| Email Processing / Concepts | |
Postfix is a Mail Transfer Agent (MTA). While other MTAs can be used (sendmail for example), Postfix is generally easiest to configure. It can be configured to send email directly from the BillMax server or through a SMTP relay..
Beginning with the Debian release of BillMax, the preferred and installed MTA is Postfix.
Regardless of which MTA is used, the Sendmail Path in must be /usr/sbin/sendmail as this is an alias to the actual command used.
Configuring the MTA to use a SMTP relay or send email directly dictates what steps are needed to setup email sending. For example, reverse DNS lookup for the BillMax server is needed if sending email directly, but generally is not needed for SMTP relays.
Using a SMTP relay is preferred over direct sending as this technique utilizes a mail server that meets (hopefully) all the requirements for sending email. However, relays generally require authentication and thus the storage of email credentials on the BillMax server. This can be problematic administratively if the mail server requires password changes over time.
Email configuration for Postfix is done in the /etc/postfix directory. See https://www.postfix.org/ for specific instructions.
Note regardless of email system used, it is not necessary to configure inbound email from external hosts for BillMax to operate. The BillMax ticketing system, if configured, uses the fetchmail program to receive such email.