I have a plugin which has its own register facility. This is on a multisite. I am using a must use plugin to send a custom activation email. This is the activation email which the user has to click in order to activate their account.

I am using the wpmu_signup_user_notification_email hook to catch the email and change the content. This is working, but the email is not html - any html such as header tags and paragraphs and br's are just included in the text.

How can I make this send a html based email.

Thank you

function my_signup_user_notification_email($content, $user_login, $user_email, $key, $meta) 
{
    $m = "<h1>Thanks for signing up</h1>";
    $m .= $content;    
    return $m;
}

add_filter('wpmu_signup_user_notification_email', 'my_signup_user_notification_email', 10, 5);

I have a plugin which has its own register facility. This is on a multisite. I am using a must use plugin to send a custom activation email. This is the activation email which the user has to click in order to activate their account.

I am using the wpmu_signup_user_notification_email hook to catch the email and change the content. This is working, but the email is not html - any html such as header tags and paragraphs and br's are just included in the text.

How can I make this send a html based email.

Thank you

function my_signup_user_notification_email($content, $user_login, $user_email, $key, $meta) 
{
    $m = "<h1>Thanks for signing up</h1>";
    $m .= $content;    
    return $m;
}

add_filter('wpmu_signup_user_notification_email', 'my_signup_user_notification_email', 10, 5);

• plugins
• multisite

1 Answer 1

Per the filter's documentation, the $content should be formatted for use by wp_mail(). In the wp_mail() documentation, I find this:

The default charset is based on the charset used on the blog. The charset can be set using the wp_mail_charset filter.

So it appears you need to explicitly allow WordPress to send HTML mail. See the User Contributed Notes section of the wp_mail_charset filter documentation.

Here's how I'd tackle your question:

/**
 * Filter the mail content type.
 */
function wpse360648_set_html_mail_content_type() {
    return 'text/html';
}
add_filter( 'wp_mail_content_type', 'wpse360648_set_html_mail_content_type' );

function wpse360648_user_notification_email( $content, $user_login, $user_email, $key, $meta ) {
    $m = "<h1>Thanks for signing up</h1>";
    $m .= $content;    
    return $m;
}

add_filter('wpmu_signup_user_notification_email', 'wpse360648_user_notification_email', 10, 5);

// Reset content-type to avoid conflicts -- https://core.trac.wordpress/ticket/23578
remove_filter( 'wp_mail_content_type', 'wpse360648_set_html_mail_content_type' );

(based on code by Helen Hou-Sandi)