You can send upto 200 emails per day (Google’s limit). We use Gmail Oauth 2.0 API.
You can setup muliple Gmail Accounts.
Amazon Simple Email Service (Amazon SES) is a highly scalable and cost-effective service.
its nearly 100x cheaper than any traditional email marketing company. Amazon has amazing infrastructure and we recommend you to use it.
Follow this simple Step by Step tutorial to set up Amazon SES Account
You can use smtp server settings from hundreds of popular bulk email providers including...

Connected Accounts
No integrations required, but all emails will be sent via
Verified Domain:

Add another Email Address that will be used for sending Emails

You will be sent a verification Email from Amazon SES. Please click on the verification link.