Pepipost is a cloud-based email delivery engine. It helps you deal with the challenge of timely delivery of your transactional and triggered emails to the inbox of your contacts. Whether your preferred mode of sending emails is SMTP relay or HTTP APIs, Pepipost has solutions for both. If you have your own mail servers/clients/application that runs on SMTP, then you would want to use SMTP. Learn more, here.
If you have online portals or mobile apps, then you would want to use HTTP. Learn more, here.