By default we block traffic to internet on tcp port 25. We do this to prevent abuse, mail abuse is very common and we do our best to prevent this from happening.
If you want to send e-mail from our platform we recommend using an external smtp relay. All major external smtp services offer their service on other ports than port 25.
This way you can get an automated reliable smtp service that normally is very cost effective.
Contact us if you want us to recommend a provider or have any other questions.