Install

<dependency>    <groupId>uk.openemail</groupId>    <artifactId>openemail</artifactId>    <version>0.0.1</version></dependency>

import java.util.Map;import uk.openemail.Body;import uk.openemail.OpenEmail; public final class FirstEmail {    public static void main(String[] args) {        OpenEmail client = new OpenEmail();         Map<String, Object> email = client.emails().send(Body.of(            "from", "Acme Billing <[email protected]>",            "to", "[email protected]",            "subject", "Your September invoice",            "html", "<p>Invoice attached.</p>"        ));         System.out.println(email.get("id") + " " + email.get("status"));    }}

new OpenEmail() reads the key from OPENEMAIL_API_KEY, so the code holds no credential. Use OpenEmail.builder().apiKey(...) when your configuration lives somewhere else.

A request body is a Map<String, Object> whose keys keep the names of the API, so scheduledAt is written the same way here as in the API reference. Body.of builds one that keeps the order you wrote it in and takes null values. A response is the decoded JSON as a Map<String, Object>, so email.get("id") reads the id.

Java 17 and up, on any JVM language. The jar has no dependency, and it names its module uk.openemail for applications on the module path.

The client is immutable and safe to share between threads. Build one when the application starts and keep it: it holds one HttpClient, which reuses its connections.