Mail properties in Production - Jhipster 4.2.8 - spring-boot

Question

I have the following configuration of the mail account of my company in develop, which goes perfectly:
mail:
host: smtp.xxx.es
port: 587
username: notifications-noreply#xxx.es
password: xxxx
protocol: smtp
#tls: true
properties.mail.smtp:
auth: true
from: notifications-noreply#xxx.es
starttls.enable: true
ssl.trust: smtp.xxx.es
I copy de same data from "application-dev.yml" to "application-prod.yml".
I make the deployment in Google Cloud.
It does not send me mails and the logs tells me the following:
: Email could not be sent to user 'joseluis.xxx#xxx.com': Mail server connection failed; nested exception is com.sun.mail.util.MailConnectException: Couldn't connect to host, port: smtp.xxx.es, 587; timeout -1;
nested exception is:
java.net.ConnectException: Operation timed out (Connection timed out). Failed messages: com.sun.mail.util.MailConnectException: Couldn't connect to host, port: smtp.xxx.es, 587; timeout -1;
nested exception is:
java.net.ConnectException: Operation timed out (Connection timed out)
Can somebody help me?

Answer 1

As described in the Google Cloud documentation you can't send e-mail from your Google Cloud VM using port 587. So this has nothing to do with JHipster, it's a limitation from your cloud provider.
I personally use Mailgun, which uses port 2525 (which is allowed by Google Cloud), here is my configuration for https://start.jhipster.tech (a JHipster application that runs on Google Cloud):
spring:
mail:
host: smtp.mailgun.org
port: 2525
username: xxxxx#mg.jhipster.tech
password: xxxxx
As Mailgun provides a generious free tier you can test this for free - in fact I use it in production and haven't paid anything yet!