Mandrill Plugin Deprecation Warning: Deprecated class-smtp.php File Usage

We are currently experiencing a warning related to the Mandrill plugin, which is impacting the site’s response time. The warning details are as follows:

Warning Message:
File class-smtp.php is deprecated since version 5.5.0! Use wp-includes/PHPMailer/SMTP.php instead. The SMTP class has been moved to the wp-includes/PHPMailer subdirectory and now uses the PHPMailer\PHPMailer namespace.

File Involved:
wp-includes/class-smtp.php on line 30

Below is the Error Trace:
Error Message:

File class-smtp.php is <strong>deprecated</strong> since version 5.5.0! Use wp-includes/PHPMailer/SMTP.php instead. The SMTP class has been moved to the wp-includes/PHPMailer subdirectory and now uses the PHPMailer\PHPMailer namespace.

in trigger_error called at /nas/content/live/megafit/wp-includes/functions.php (6085)
in wp_trigger_error called at /nas/content/live/megafit/wp-includes/functions.php (5799)
in _deprecated_file called at /nas/content/live/megafit/wp-includes/class-smtp.php (6)
in require_once called at /nas/content/live/megafit/wp-content/plugins/send-emails-with-mandrill/legacy/function.wp_mail.php (13)
in require called at /nas/content/live/megafit/wp-content/plugins/send-emails-with-mandrill/lib/wpMandrill.class.php (1750)
in wpMandrill::wp_mail_native called at /nas/content/live/megafit/wp-includes/class-wp-hook.php (324)
in WP_Hook::apply_filters called at /nas/content/live/megafit/wp-includes/class-wp-hook.php (348)
in WP_Hook::do_action called at /nas/content/live/megafit/wp-includes/plugin.php (517)
in do_action called at /nas/content/live/megafit/wp-content/plugins/send-emails-with-mandrill/lib/wpMandrill.class.php (44)
in wp_mail called at /nas/content/live/megafit/wp-content/plugins/woocommerce/includes/emails/class-wc-email.php (741)
in WC_Email::send called at /nas/content/live/megafit/wp-content/plugins/woocommerce-subscriptions/vendor/woocommerce/subscriptions-core/includes/emails/class-wcs-email-processing-renewal-order.php (101)
in WCS_Email_Processing_Renewal_Order::trigger called at /nas/content/live/megafit/wp-includes/class-wp-hook.php (324)
in WP_Hook::apply_filters called at /nas/content/live/megafit/wp-includes/class-wp-hook.php (348)
in WP_Hook::do_action called at /nas/content/live/megafit/wp-includes/plugin.php (517)
in do_action called at /nas/content/live/megafit/wp-content/plugins/woocommerce-subscriptions/vendor/woocommerce/subscriptions-core/includes/class-wc-subscriptions-email.php (151)
in WC_Subscriptions_Email::send_renewal_order_email called at /nas/content/live/megafit/wp-includes/class-wp-hook.php (326)
in WP_Hook::apply_filters called at /nas/content/live/megafit/wp-includes/class-wp-hook.php (348)
in WP_Hook::do_action called at /nas/content/live/megafit/wp-includes/plugin.php (517)
in do_action called at /nas/content/live/megafit/wp-content/plugins/woocommerce/includes/class-wc-order.php (420)
in WC_Order::status_transition called at /nas/content/live/megafit/wp-content/plugins/woocommerce/includes/class-wc-order.php (253)

can you help?