PHPMailer
A project using Symfony packages
PHPMailer is a full-featured email creation and transfer class for PHP. Used by many popular open-source projects, it can send emails without a local mail server. It supports DKIM and S/MIME signing and SMTP authentication with LOGIN, PLAIN, NTLM, CRAM-MD5 and Google's XOAUTH2 mechanisms over SSL and TLS transports.
Official website: github.com/PHPMailer/PHPMailer