8. Sending mails

Spring Cloud AWS provides an XML element to configure a Spring org.springframework.mail.MailSender implementation for the client to be used. The default mail sender works without a Java Mail dependency and is capable of sending messages without attachments as simple mail messages. A configuration with the necessary elements will look like this:

<beans xmlns:aws-mail="http://www.springframework.org/schema/cloud/aws/mail"
   xsi:schemaLocation="http://www.springframework.org/schema/cloud/aws/mail
      http://www.springframework.org/schema/cloud/aws/mail/spring-cloud-aws-mail.xsd">

	<aws-context:context-credentials>
	  ..
	</aws-context:context-credentials>

	<aws-context:context-region region="eu-west-1" />

	<aws-mail:mail-sender id="testSender" />

</beans>

Application developers can inject the MailSender into their application code and directly send simple text based e-mail messages. The sample below demonstrates the creation of a simple mail message.

public class MailSendingService {

	private MailSender mailSender;

	@Autowired
	public MailSendingService(MailSender mailSender) {
		this.mailSender = mailSender;
	}

	public void sendMailMessage() {
		SimpleMailMessage simpleMailMessage = new SimpleMailMessage();
		simpleMailMessage.setFrom("[email protected]");
		simpleMailMessage.setTo("[email protected]");
		simpleMailMessage.setSubject("test subject");
		simpleMailMessage.setText("test content");
		this.mailSender.send(simpleMailMessage);
	}
}

Sending attachments with e-mail requires MIME messages to be created and sent. In order to create MIME messages, the Java Mail dependency is required and has to be included in the classpath. Spring Cloud AWS will detect the dependency and create a org.springframework.mail.javamail.JavaMailSender implementation that allows to create and build MIME messages and send them. A dependency configuration for the Java Mail API is the only change in the configuration which is shown below.

<dependency>
	<groupId>javax.mail</groupId>
	<artifactId>mailapi</artifactId>
	<version>1.4.1</version>
	<exclusions>
		<!-- exclusion because we are running on Java 1.7 that includes the activation API by default-->
		<exclusion>
			<artifactId>activation</artifactId>
			<groupId>javax.activation</groupId>
		</exclusion>
	</exclusions>
</dependency>

	Note
	Even though there is a dependency to the Java Mail API there is still the Amazon SES API used underneath to send mail messages. There is no SMTP setup required on the Amazon AWS side.

Sending the mail requires the application developer to use the JavaMailSender to send an e-mail as shown in the example below.

public class MailSendingService {

	private JavaMailSender mailSender;

   	@Autowired
	public MailSendingService(JavaMailSender mailSender) {
		this.mailSender = mailSender;
	}

	public void sendMailMessage() {
		this.mailSender.send(new MimeMessagePreparator() {

   			@Override
   			public void prepare(MimeMessage mimeMessage) throws Exception {
   				MimeMessageHelper helper =
   					new MimeMessageHelper(mimeMessage, true, "UTF-8");
   				helper.addTo("[email protected]");
   				helper.setFrom("[email protected]");
   				helper.addAttachment("test.txt", ...);
   				helper.setSubject("test subject with attachment");
   				helper.setText("mime body", false);
   			}
   		});
	}
}

Amazon SES is not available in all regions of the Amazon Web Services cloud. Therefore an application hosted and operated in a region that does not support the mail service will produce an error while using the mail service. Therefore the region must be overridden for the mail sender configuration. The example below shows a typical combination of a region (EU-CENTRAL-1) that does not provide an SES service where the client is overridden to use a valid region (EU-WEST-1).

<beans ...>

 <aws-context:context-region region="eu-central-1" />
 <aws-mail:mail-sender id="testSender" region="eu-west-1"/>

</beans>

To avoid any spam attacks on the Amazon SES mail service, applications without production access must verify each e-mail receiver otherwise the mail sender will throw a com.amazonaws.services.simpleemail.model.MessageRejectedException.

Production access can be requested and will disable the need for mail address verification.