Problems using WP Mail SMTP

bbpress-notify-nospam uses wp_mail() function to send out the messages, and sets a default ‘From’ address.

You can modify the headers by hooking into the bbpnns_extra_headers filter to either modify the ‘From’ or remove it altogether (which should let WP Mail SMTP do its thing).

$headers = sprintf("From: %s <%s>\r\n", get_option('blogname'), get_bloginfo('admin_email'));
$headers = apply_filters('bbpnns_extra_headers', $headers, $recipients, $subject, $body);

Example code:

function remove_bbpnns_header( $headers )
{
    return null;
}
add_filter('bbpnns_extra_headers', 'remove_bbpnns_header');