Many PHP developers utilize email in their code. The only PHP function that supports this is the mail() function. However, it does not provide any assistance for making use of popular features such as HTML-based emails and attachments.
Formatting email correctly is surprisingly difficult. There are myriad overlapping RFCs, requiring tight adherence to horribly complicated formatting and encoding rules - the vast majority of code that you'll find online that uses the mail() function directly is just plain wrong!
*Please* don't be tempted to do it yourself - if you don't use PHPMailer, there are many other excellent libraries that you should look at before rolling your own - try SwiftMailer, Zend_Mail, eZcomponents etc.
The PHP mail() function usually sends via a local mail server, typically fronted by a `sendmail` binary on Linux, BSD and OS X platforms, however, Windows usually doesn't include a local mail server; PHPMailer's integrated SMTP implementation allows email sending on Windows platforms without a local mail server.
PHPMailer is available via [Composer/Packagist](https://packagist.org/packages/phpmailer/phpmailer). Alternatively, just copy the contents of the PHPMailer folder into somewhere that's in your PHP `include_path` setting. If you don't speak git or just want a tarball, click the 'zip' button at the top of the page in GitHub.
PHPMailer provides an SPL-compatible autoloader, and that is the preferred way of loading the library - just `require '/path/to/PHPMailerAutoload.php';` and everything should work. The autoloader does not throw errors if it can't find classes so it prepends itself to the SPL list, allowing your own (or your framework's) autoloader to catch errors. SPL autoloading was introduced in PHP 5.1.0, so if you are using a version older than that you will need to require/include each class manually.
While installing the entire package manually or with composer is simple, convenient and reliable, you may want to include only vital files in your project. At the very least you will need [class.phpmailer.php](class.phpmailer.php). If you're using SMTP, you'll need [class.smtp.php](class.smtp.php), and if you're using POP-before SMTP, you'll need [class.pop3.php](class.pop3.php). For all of these, we recommend you use [the autoloader](PHPMailerAutoload.php) too as otherwise you will either have to `require` all classes manually or use some other autoloader. You can skip the [language](language/) folder if you're not showing errors to users and can make do with English-only errors. You may need the additional classes in the [extras](extras/) folder if you are using those features, including NTLM authentication, advanced HTML-to-text conversion and ics generation.
PHPMailer defaults to English, but in the [language](language/) folder you'll find numerous (39 at the time of writing) translations for PHPMailer error messages that you may encounter. Their filenames contain [ISO 639-1](http://en.wikipedia.org/wiki/ISO_639-1) language code for the translations, for example `fr` for French. To specify a language, you need to tell PHPMailer which one to use, like this:
We welcome corrections and new languages - if you're looking for corrections to do, run the [phpmailerLangTest.php](test/phpmailerLangTest.php) script in the tests folder and it will show any missing translations.
You'll find some basic user-level docs in the [docs](docs/) folder, and you can generate complete API-level documentation using the [generatedocs.sh](docs/generatedocs.sh) shell script in the docs folder, though you'll need to install [PHPDocumentor](http://www.phpdoc.org) first. You may find [the unit tests](test/phpmailerTest.php) a good source of how to do various operations such as encryption.
Some useful information on troubleshooting and bulk sending with PHPMailer can be found in the [Github wiki](https://github.com/PHPMailer/PHPMailer/wiki).
With the move to the PHPMailer GitHub organisation, you'll need to update any remote URLs referencing the old GitHub location with a command like this from within your clone: