For various reasons (transactional, marketing, etc.) you might want to send emails from your application. Scalingo does not provide an embedded email server, we are not an email provider. If you try to use the sendmail executable, you will not find it.

However it is is totally possible to send emails, thanks to an external SMTP server.

Use of an external SMTP server

As email sending is an entirely other job, we encourage you to use services specialized into that. Here is a list containing a few actors on the market of email as a service:

• Brevo (formerly Sendinblue)
• Sarbacane Campaigns
• Mailjet
• Mailchimp
• Sendgrid
• Amazon SES

This list is not exclusive, but all of them will work perfectly with Scalingo. In each case, create an account, register a new sending domain and sending address, add the credentials in your app environment variables and use them.

Port 25 disabled

SMTP servers are usually available on different ports: 25 (SMTP), 465 (SMTPS), 587 (submission). Port 25 is usually unencrypted and sometimes unauthenticated. For this reason, such servers are often used as spam relay.

Our decision has been to block the port 25, but don’t worry, all providers listed above (and a lot of others) are using the port 587 when giving you the server connection string.