PHPMailer Properties Reference

Every public property of PHPMailer 6.x you are likely to set, with its type, default and what it actually changes. Properties are set directly on the instance. There are no setters for most of them:

$mail->Host    = 'smtp.example.com';
$mail->Port    = 587;
$mail->CharSet = PHPMailer::CHARSET_UTF8;

SMTP connection

On $SMTPOptions: the snippet that disables verify_peer circulates widely as a fix for certificate errors. It works by turning off the verification TLS exists to provide. Fix the CA bundle instead, openssl.cafile in php.ini. Disabling verification against a production server means any machine on the path can read the credentials you are about to send.

Debugging

$mail->Debugoutput = function ($str, $level) {
    error_log('PHPMailer: ' . trim($str));
};

Sender and recipients

$Sender is worth setting deliberately. Bounces go to the envelope sender, so pointing it at a monitored mailbox is how you learn which addresses are dead. Rather than sending to them forever and eroding your reputation.

Content

The $CharSet default catches everyone eventually. ISO-8859-1 cannot represent an em dash, a curly quote, or any non-Latin script, and the result is mojibake in the recipient’s client. Set UTF-8 unless you have a specific reason not to.

Headers and metadata

DKIM

$mail->DKIM_domain   = 'example.com';
$mail->DKIM_selector = 'phpmailer';
$mail->DKIM_private  = '/secure/dkim_private.pem';
$mail->DKIM_identity = $mail->From;

Transport

Constants worth knowing

Prefer the constants to their string values. They are self-documenting, and a typo in 'startls' fails at runtime while ENCRYPTION_STARTLS fails immediately.

A sane baseline

$mail = new PHPMailer(true);

$mail->isSMTP();
$mail->Host       = getenv('SMTP_HOST');
$mail->Port       = 587;
$mail->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
$mail->SMTPAuth   = true;
$mail->Username   = getenv('SMTP_USER');
$mail->Password   = getenv('SMTP_PASS');
$mail->Timeout    = 30;
$mail->CharSet    = PHPMailer::CHARSET_UTF8;
$mail->XMailer    = ' '; // omit the X-Mailer header
$mail->Sender     = 'bounces@example.com';

Rather than repeating this everywhere, put it in a subclass, see Extending PHPMailer.

See also

• Methods Reference — signatures for every method.
• SMTP Example — these properties in context, with the errors they cause.
• Examples — complete scripts per transport.
• Tutorial — the guided introduction.

Properties in practice

• From, Sender, Reply-To and the envelope sender — the properties that decide SPF alignment.
• certificate verify failed — what SMTPOptions really overrides.
• UTF-8, accents and encoding — CharSet and Encoding explained.
• DKIM signature body hash did not verify — when the DKIM_* properties are right and the signature still fails.