Yes. Rebilly has an API and webhook notifications. Between the two, you should be able to connect it to any other system. Rebilly has some built-in integrations, such as with some Email Service Providers (like Mailgun, Sendgrid, and AWS SES).
If you have any questions or need assistance with implementing Rebilly, please contact us. You can email us at firstname.lastname@example.org, chat with us or schedule a talk with a billing specialist below.