Swift Mailer
From Wiki @ Karl Jones dot com
Swift Mailer is a free PHP-based library for sending email.
Description
"Swift Mailer integrates into any web app written in PHP 5, offering a flexible and elegant object-oriented approach to sending emails with a multitude of features."
- Send emails using SMTP, sendmail, postfix or a custom Transport implementation of your own
- Support servers that require username & password and/or encryption
- Protect from header injection attacks without stripping request data content
- Send MIME compliant HTML/multipart emails
- Use event-driven plugins to customize the library
- Handle large attachments and inline/embedded images with low memory use
It is released under the MIT License.