Swift Mailer settings for Cloud Platform

Symfony Mailer and Symfony Mailer Lite (which is a drop-in replacement for Swift Mailer) have specific installation instructions on the Acquia Platform.

Issue

When using the Swift Mailer Drupal module for both Cloud Classic and Cloud Platform, emails might not be sent.

Error message:

Expected response code 220 but got code "", with message "unknown shorthand flag: 'b' in -bs

Resolution

Configure Swift Mailer module in the Drupal admin user interface so that it uses the sendmail transport, using the t mode. Here is an example screenshot: