<dependency>
    <groupId>com.sendgrid</groupId>
    <artifactId>sendgrid-java</artifactId>
    <version>4.10.0</version> 
</dependency>

import com.sendgrid.*;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;

import java.io.IOException;

@Service
public class EmailService {

    @Value("${sendgrid.api.key}")
    private String sendGridApiKey;

    public void sendEmail(String to, String subject, String body) throws IOException {
        Email from = new Email("your-email@example.com"); // replace your sender email
        Email toEmail = new Email(to);
        Content content = new Content("text/plain", body);
        Mail mail = new Mail(from, subject, toEmail, content);

        SendGrid sg = new SendGrid(sendGridApiKey);
        Request request = new Request();
        try {
            request.setMethod(Method.POST);
            request.setEndpoint("mail/send");
            request.setBody(mail.build());
            Response response = sg.api(request);
            System.out.println(response.getStatusCode());
            System.out.println(response.getBody());
            System.out.println(response.getHeaders());
        } catch (IOException ex) {
            throw ex;
        }
    }
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class EmailController {

    @Autowired
    private EmailService emailService;

    @PostMapping("/send-email")
    public String sendEmail(@RequestParam String to, @RequestParam String subject, @RequestParam String body) {
        try {
            emailService.sendEmail(to, subject, body);
            return "Email sent successfully!";
        } catch (IOException e) {
            return "Error sending email: " + e.getMessage();
        }
    }
}