如何在wordpress插件中使用PHP发送HTML电子邮件

Question

I use the plugin to create custom login and register page in wordpress. Everything works well with one exception. I want to send Html email for new user and lost password,but when changing templates does not work. Emails are displayed with all html tags.Is there a way to change it so I can send html emails? The code in the plugin is as follows:

$body = <<< TEXT
Hi {$user},

Thank you for registering with us, here is your registration information. 

Login Username: {$user}
Email: {$user_email} 
Password: ==SECRET==

You can update it anytime by going to {$site_url}

Thanks
{$site_name}
TEXT;