Linux Server Thunderbird Email Configuration

My server is a VPS hosted by Contabo.com. The VPS runs Virtualmin/Webmin with Ubuntu Linux 20.04.5. Locally, I run Thunderbird on an iMac with Venutura 13.6.3. The outgoing server is Gmail, because I keep getting an error message when I select my own server to send emails. The message is: Sending of the message failed. Unable to communicate securely with peer: requested domain name does not match the server’s certificate. The configuration related to [login to view URL] must be corrected. The SSL certificate appears to be valid. It's a Let's Encrypt SSL that auto renews every 3 months. I've tried changing the port, changing the outgoing server to [login to view URL] instead of [login to view URL], but still the error appears. I'm able to send emails via [login to view URL], port 587, which is another mail service that is also hosted on the server. This job requires someone to adjust the settings so that I can send mail from the domain andrewscottmusic.com. You must have experience with Virtualmin and Thunderbird. In the FIRST line of your application state your experience with Virtualmin and Thunderbird,and how you would fix this problem. It's likely that there will be many applications for this job – too many for me to acknowledge individually. If you are unsuccessful, I thank you for your time and wish you better luck in your next proposal. NO placemarker bids. Quote your price for the job – NOT your hourly rate. NO phone calls or emails; Freelancer applications only