application.yml

spring_boot_enviando_email_application.yml

spring:
  # ... outras configurações
  mail:
    host: smtp.gmail.com
    port: 587
    protocol: smtp
    username: <seu_email>@gmail.com
    password: <chave de 16 digitos gerada pelo Google Account>
    properties:
        mail:
            smtp:
                auth: true
                starttls:
                    enable: true
                    required: true
                quitwait: false