We tried to use the standard option with sendgrid first and the same happened. Was created a sendgrid account and mailgun account. A test with curl worked sending email to my test email box.
Thanks for your reply, but your configuration seems to use a custom mailer, if I understood right. We are trying to configure the coherence mailer, which seems to be fully prepared to create the e-mail and send it.
Our problem is that, even with all configuration in place exactly as shown in Coherence docs, nothing is sent. We see the e-mail created, we see all the preparation and we see that was sent successfully but nothing is really sent.