As part of our project firefly application we want to send out an email to the users, is there any email service available or we should rely on services like SES in AWS and Sendgrid to send an email?
@kishoreindraganti - the backend of your Firefly app is a set of serverless actions on I/O Runtime. You can write any nodejs code there.
However, we don't provide email service. You could use Adobe Campaign for marketing email delivery, or a third party email service (e.g. called from your Runtime actions using REST APIs)