spring.mail.host=smtp.gmail.com
spring.mail.port=465
spring.mail.protocol=smtp
spring.mail.username=xxx@gmail.com
spring.mail.password=xxx
spring.mail.from=xxx@gmail.com

<version>2.0.3.RELEASE</version>
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-mail</artifactId>
</dependency>