Hello,
The free Indy version only supports openSSL 1.1.1, openSSL 3.0 is only supported with a newer Indy version and is only available for Enterprise customers.
I think that if you open
https://www.howsmyssl.com it tests the web-browser connection, not your indy SMTP application.
The error means the client is trying to connect using a old TLS protocol which is not supported by the server, maybe the application is misconfigured, is still pointing to old Indy version, the openssl libraries are not updated...
Kind Regards,
Sergio