sendEmail abstract method
Sends an email from from to recipients at the given domain.
body is the full email content including headers.
If useTls is true, attempts to use STARTTLS when supported.
Returns true if the email was accepted by the remote server.
Implementation
Future<bool> sendEmail({
required String domain,
required String from,
required List<String> recipients,
required String body,
bool useTls,
});