Swift mailer Failed to authenticate on SMTP server with username

Recently we started using Amazon SES to send email out from a Symfony2 app. We struck an issue where mail wouldn’t send and in the dev log we had the following error


app.ERROR: Exception occurred while flushing email queue: Failed to authenticate on SMTP server with username "USERNAME" using 2 possible authenticators [] []

The issues is caused by the encryption and port missing from the swift mailer configuration. In your app/config/config.yml make sure your swift mailer configuration looks like the following. You need to add the encryption and port directives.


swiftmailer:
transport: "%mailer_transport%"
host: "%mailer_host%"
username: "%mailer_user%"
password: "%mailer_password%"
encryption: %mailer_encryption%
port: %mailer_port%
spool: { type: memory }