EmailTemplate module: 2 emails sent, then connection time out
I'm trying to send emails through the EmailTemplate module. We use a mail server from the client (no TLS/SSL, port 25). On one application all works well, on the other application after 2 emails nothing is sent anymore. Every mail will get a connection time out error, no matter the trigger or template (including the connection test email). Only a restart of the environment will solve it for the first 2 emails and after that, again connection time out. When we receive a connection time out, no incoming connection is registered on the client side. So it seems to be an application issue, not being able to send data out. Does anyone recognise this or have an idea where to start debugging? I'm kinda stuck here!
Sytze de Bok
Is your application running in Mendix cloud v4? We experienced the same problem running two apps in cloud v4: only 5 SMTP messages a day were sent, the rest got a timeout.
Please note that you cannot send email from Mendix Cloud v4 over port 25. Although this port is open, it is heavily rate-limited by the infrastructure provider, so you will experience issues. This configuration cannot be changed.
Your SMTP provider needs to expose a secure port like 587, which is a best practice that most modern providers offer out of the box.
We solved the problem by using a connection to the same mailserver on port 587 (first plain SMTP traffic and after some more testing by using TLS).