PHPMailer is a PHP class for PHP (www.php.net) that provides a package of functions to send email. The two primary features are sending HTML Email and e-mails with attachments. PHPMailer supports nearly all possiblities to send email: mail(), Sendmail, qmail & direct to SMTP server. You can use any feature of SMTP-based e-mail, multiple recepients via to, CC, BCC, etc. In short: PHPMailer is an efficient way to send e-mail within PHP
Unlimited PHP Mailer is usually created from the Linux Server Root . Since it was created on the server so there isn’t limit to the process of sending email.