lh_multipart_email_destroy_phpmailerDefault false. When several emails are sent in one request, WordPress reuses its PHPMailer object, and the plain text part from one email would otherwise carry over to the next. By default the plugin just clears that plain text part. Return true to destroy the PHPMailer object instead, so WordPress builds a fresh one for the next email; if WP Mail SMTP is active, its mailer is recreated in its place. Before 1.15.0 this filter was named lh-multipart-email_destroy-phpmailer.
add_filter( 'lh_multipart_email_destroy_phpmailer', '__return_true' );lh_multipart_email_return_plugin_debugging_statusDefault false. Return true to write the plugin’s log lines to debug.log; WP_DEBUG must also be true.
lh_multipart_email_phpmailer_reinitializedFires after the PHPMailer object has been cleared or destroyed between two emails sent in the same request, for code that needs to work with the mailer at that point. Before 1.15.0 this action was named lh-multipart-email_phpmailer_reinitialized.