I have an PHP Forum (vanilla forums) and for its registration emails I installed Postfix. Now As I figured it out, vanilla forums uses PHPMailer for email sending procedure.Now my questions are:  Is Postfix an SMTP Server? Could it fulfill the requirements that PHPMailer needs to send registration emails?  Should I install a separate SMTP Server for this kind jobs? (i.e scripts like PHPMailer that need SMTP Server). If yes Which SMTP Server should I install?Does installing a separate SMTP Server conflict with Postfix? 
Postfix, SMTP Server, PHPMailer
postfix;smtp;mta