Using groovy script to send email (inside a DS or CS)?

Your best bet is to modify something like Email_RoundTrip or Email_TransitTime to just do the SMTP parts. You will still need to provide some email server to sent to, but it can be M365, gmail or whatever your company uses for email. You don’t need to setup a real email server for this.

I personally would do these types of tasks outside of LM. Like using a utility server to run scripts on a scheduled basis. But I understand if you don’t have access to something like that.