I am creating an Android app which needs the user to be registered. For registering I need to send email and SMS with verification code from my servers for which I intend to write a web service.
I would like to know the best and cheapest way to send email and SMS to initially 1000 to 5000 users and if my app becomes popular what is the best option to scale?
Is it cheaper to setup our own email and SMS gateway or use third party in the beginning?
Did you check out Amazon web services? https://aws.amazon.com/sns/pricing/