WP_PHPMailer

Last updated: February 12, 2026

WordPress extension of PHPMailer providing internationalized error messages.

Since: 6.8.0
Source: wp-includes/class-wp-phpmailer.php
Extends: PHPMailerPHPMailerPHPMailer

Purpose

WP_PHPMailer overrides PHPMailer’s language handling to use WordPress’s internationalization system (__()). This ensures error messages are translated according to the site’s locale rather than PHPMailer’s built-in language files.

Constructor

public function __construct( $exceptions = false )

Parameter	Type	Default	Description
`$exceptions`	bool	`false`	Whether to throw exceptions for errors

Calls parent constructor and immediately sets language strings.

Methods

setLanguage()

public static function setLanguage( $langcode = 'en', $lang_path = '' )

Overrides PHPMailer’s setLanguage() to populate static::$language with WordPress-translated strings.

Parameter	Type	Default	Description
`$langcode`	string	`'en'`	Unused. Ignored by WordPress implementation
`$lang_path`	string	`''`	Unused. Ignored by WordPress implementation

Returns: true (always)

Translated Error Messages

Key	English Message
`authenticate`	SMTP Error: Could not authenticate.
`buggy_php`	Your version of PHP is affected by a bug…
`connect_host`	SMTP Error: Could not connect to SMTP host.
`data_not_accepted`	SMTP Error: Data not accepted.
`empty_message`	Message body empty
`encoding`	Unknown encoding:
`execute`	Could not execute:
`extension_missing`	Extension missing:
`file_access`	Could not access file:
`file_open`	File Error: Could not open file:
`from_failed`	The following From address failed:
`instantiate`	Could not instantiate mail function.
`invalid_address`	Invalid address:
`invalid_header`	Invalid header name or value
`invalid_hostentry`	Invalid host entry:
`invalid_host`	Invalid host:
`mailer_not_supported`	mailer is not supported.
`provide_address`	You must provide at least one recipient email address.
`recipients_failed`	SMTP Error: The following recipients failed:
`signing`	Signing Error:
`smtp_code`	SMTP code:
`smtp_code_ex`	Additional SMTP info:
`smtp_connect_failed`	SMTP connect() failed.
`smtp_detail`	Detail:
`smtp_error`	SMTP server error:
`variable_set`	Cannot set or reset variable:
`no_smtputf8`	Server does not support SMTPUTF8 needed to send to Unicode addresses
`imap_recommended`	Using simplified address parser is not recommended…
`deprecated_argument`	Argument $useimap is deprecated

Usage

WordPress automatically uses WP_PHPMailer when wp_mail() is called:

// In wp_mail() - wp-includes/pluggable.php
if ( ! ( $phpmailer instanceof PHPMailerPHPMailerPHPMailer ) ) {
    require_once ABSPATH . WPINC . '/PHPMailer/PHPMailer.php';
    require_once ABSPATH . WPINC . '/PHPMailer/SMTP.php';
    require_once ABSPATH . WPINC . '/PHPMailer/Exception.php';
    require_once ABSPATH . WPINC . '/class-wp-phpmailer.php';
    $phpmailer = new WP_PHPMailer( true );

    $phpmailer::$validator = static function ( $email ) {
        return (bool) is_email( $email );
    };
}

Note: WordPress sets $exceptions = true and replaces PHPMailer’s email validator with WordPress’s is_email() function.

Inherited Properties

Key properties from PHPMailerPHPMailerPHPMailer:

Property	Type	Default	Description
`$Mailer`	string	`'mail'`	Send method: mail, sendmail, smtp
`$Host`	string	`'localhost'`	SMTP host(s)
`$Port`	int	`25`	SMTP port
`$SMTPAuth`	bool	`false`	Enable SMTP authentication
`$Username`	string	`''`	SMTP username
`$Password`	string	`''`	SMTP password
`$SMTPSecure`	string	`''`	Encryption: ”, ‘tls’, ‘ssl’
`$SMTPAutoTLS`	bool	`true`	Auto-enable TLS if supported
`$From`	string	`''`	From email address
`$FromName`	string	`''`	From name
`$Subject`	string	`''`	Email subject
`$Body`	string	`''`	Email body (HTML or plain)
`$AltBody`	string	`''`	Plain-text alternative body
`$CharSet`	string	`'iso-8859-1'`	Character set
`$ContentType`	string	`'text/plain'`	MIME content type
`$Encoding`	string	`'8bit'`	Message encoding
`$Timeout`	int	`300`	SMTP timeout in seconds
`$SMTPDebug`	int	`0`	Debug output level (0-4)

Inherited Methods

Method	Description
`send()`	Send the email
`isMail()`	Set mailer to use PHP mail()
`isSMTP()`	Set mailer to use SMTP
`isSendmail()`	Set mailer to use sendmail
`setFrom($address, $name)`	Set From address
`addAddress($address, $name)`	Add To recipient
`addCC($address, $name)`	Add CC recipient
`addBCC($address, $name)`	Add BCC recipient
`addReplyTo($address, $name)`	Add Reply-To address
`addAttachment($path, $name)`	Add file attachment
`addEmbeddedImage(...)`	Add inline embedded image
`addCustomHeader($header)`	Add custom header
`isHTML($isHtml)`	Set HTML mode
`clearAllRecipients()`	Clear all recipients
`clearAttachments()`	Clear attachments
`clearCustomHeaders()`	Clear custom headers
`clearReplyTos()`	Clear Reply-To addresses

Constants

From PHPMailerPHPMailerPHPMailer:

// Character sets
const CHARSET_ASCII = 'us-ascii';
const CHARSET_ISO88591 = 'iso-8859-1';
const CHARSET_UTF8 = 'utf-8';

// Content types
const CONTENT_TYPE_PLAINTEXT = 'text/plain';
const CONTENT_TYPE_TEXT_HTML = 'text/html';
const CONTENT_TYPE_MULTIPART_ALTERNATIVE = 'multipart/alternative';
const CONTENT_TYPE_MULTIPART_MIXED = 'multipart/mixed';
const CONTENT_TYPE_MULTIPART_RELATED = 'multipart/related';

// Encodings
const ENCODING_7BIT = '7bit';
const ENCODING_8BIT = '8bit';
const ENCODING_BASE64 = 'base64';
const ENCODING_QUOTED_PRINTABLE = 'quoted-printable';

// Encryption
const ENCRYPTION_STARTTLS = 'tls';
const ENCRYPTION_SMTPS = 'ssl';