Sendmail and Postfix

Sendmail and Postfix are MTAs with similar capabilities. Postfix is generally easier to configure. Either can be configured to send email directly from the BillMax server or thru a SMTP relay.

On CentOS, the MTA used is specified via the
alternatives --config mta
command. Note the default MTA is Sendmail. If you want to use Postfix, in addition to the alternatives command, you may need to install Postfix first via
yum install postfix
Regardless of which MTA is used, Sendmail Path in System Administration > Global Options 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 Sendmail is done in the /etc/mail directory. See for specific instructions.

Email configuration for Postfix is done in the /etc/postfix directory. See 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.