在 WordPress 6.9 版本之前，简单配置SMTP服务是这样的。

以QQ邮箱代发为例：

add_action('phpmailer_init', function ($phpmailer) {
    $phpmailer->FromName = '手里有只毛毛虫'; //发件人名称
    $phpmailer->Host = 'smtp.qq.com';
    $phpmailer->Port = '465';
    $phpmailer->Username = '[email protected]'; //发件人邮箱
    $phpmailer->Password = 'Password'; //发件人密码
    $phpmailer->From = '[email protected]'; //发件人邮箱
    $phpmailer->SMTPAuth = true;
    $phpmailer->SMTPSecure = 'ssl';
    $phpmailer->IsSMTP();
});

而6.9版本对 wp_mail（） 函数进行了改动，变成扩展的方式设置发送地址。

更新文档：Improved Email Handling and Inline Image Support

新版导致的错误：

[email protected] : MAIL FROM command failed,Mail from address must be same as authorization user. ,501, SMTP 服务器错误：MAIL FROM command failed 详情：Mail from address must be same as authorization user. SMTP 代码：501

要恢复正常，需要追加以下设置

add_filter('wp_mail_from', function () {
    return '[email protected]'; //发件人邮箱
});