You need to test a registration flow where an OTP is sent to email. How do you automate this in Cucumber?

<dependency>
    <groupId>com.mailosaur</groupId>
    <artifactId>mailosaur-java</artifactId>
    <version>7.x</version>
</dependency>

@regression @email-verification
Scenario: Register with email OTP verification
  Given the user is on the registration page
  When the user registers with a unique Mailosaur email
  And the OTP is received in the inbox
  And the user enters the received OTP on the verification page
  Then the user account should be activated
  And the welcome email should be received

package stepDefinitions;

import com.mailosaur.MailosaurClient;
import com.mailosaur.models.*;

public class OtpSteps {
    private final ScenarioContext ctx;
    private static final String MAILOSAUR_API_KEY  = System.getenv("MAILOSAUR_API_KEY");
    private static final String MAILOSAUR_SERVER_ID = System.getenv("MAILOSAUR_SERVER_ID");

    public OtpSteps(ScenarioContext ctx) { this.ctx = ctx; }

    @When("the user registers with a unique Mailosaur email")
    public void registerWithMailosaurEmail() throws Exception {
        // Mailosaur generates: <anything>@<server-id>.mailosaur.net
        ctx.testEmail = "qa-" + System.currentTimeMillis()
            + "@" + MAILOSAUR_SERVER_ID + ".mailosaur.net";

        ctx.registrationPage.enterEmail(ctx.testEmail);
        ctx.registrationPage.enterPassword("Test@1234");
        ctx.registrationPage.clickRegister();
    }

    @When("the OTP is received in the inbox")
    public void waitForOtpEmail() throws Exception {
        MailosaurClient mailosaur = new MailosaurClient(MAILOSAUR_API_KEY);

        MessageSearchCriteria criteria = new MessageSearchCriteria()
            .withSentTo(ctx.testEmail)
            .withSubject("Your verification code");

        // Wait up to 30 seconds for the email to arrive
        Message email = mailosaur.messages().get(
            MAILOSAUR_SERVER_ID,
            criteria,
            new MessageSearchOptions().withTimeout(30000)
        );

        // Extract OTP from email body (e.g., "Your OTP is: 847291")
        String body = email.text().body();
        ctx.otp = body.replaceAll(".*Your OTP is: (\\d{6}).*", "$1");
        System.out.println("OTP received: " + ctx.otp);
    }

    @When("the user enters the received OTP on the verification page")
    public void enterOtp() {
        ctx.driver.findElement(By.id("otp-field")).sendKeys(ctx.otp);
        ctx.driver.findElement(By.id("verify-btn")).click();
    }
}

@When("the OTP is received in the inbox")
public void getOtpFromDatabase() {
    // Wait for OTP to be written to DB
    String otp = null;
    for (int i = 0; i < 30; i++) {
        otp = dbUtils.query(
            "SELECT otp FROM otp_codes WHERE email = ? AND used = false ORDER BY created_at DESC LIMIT 1",
            ctx.testEmail
        );
        if (otp != null) break;
        Thread.sleep(1000);
    }
    ctx.otp = otp;
}

# Start MailHog locally or in Docker
docker run -p 1025:1025 -p 8025:8025 mailhog/mailhog

// Query MailHog REST API
Response response = given()
    .baseUri("http://localhost:8025")
    .when()
    .get("/api/v1/messages");

String otp = response.jsonPath().getString("items[0].Content.Body")
    .replaceAll(".*OTP: (\\d{6}).*", "$1");

public class ScenarioContext {
    public WebDriver driver;
    public String testEmail;
    public String otp;
    // ...
}