ssl fixed for mail server and check customer didn't received mail after order confirmation on magento 2

Job fixed remotely with any desk or team viewer. I am having issues with an SSL certificate that appears to not have been installed correctly on my mail server and Magento 2 platform. This is causing an issue in which customers are not receiving confirmation emails once they complete an order. I need some help to get this fixed quickly so that customers can be assured that their orders have been placed and received as intended.