wp_mail 默认参数

wp_mail( $to, $subject, $message, $headers, $attachments );

headers

$headers = 'Content-type: text/html';
wp_mail( $to, $subject, $message, $headers );

$headers = array( 'Content-type: text/html' );
wp_mail( $to, $subject, $message, $headers );

Change content type

add_filter( 'wp_mail_content_type', 'rw_change_email_content_type' );
function rw_change_email_content_type( $content_type )
{
    return 'text/html';
}

Change full headers

add_filter( 'wp_mail', 'rw_change_email_headers' );
function rw_change_email_headers( $params )
{
    $params['headers'] = 'Content-type: text/html';
    return $params;
}

via wp_mail