Relay means 'to receive and pass on'. That's what an SMTP relay does. Flowmailer receives the email that needs to be delivered and then does exactly that. Every application that sends email (CRM, ESP, CDP, WMS) has a default SMTP server set up to deliver emails. But since email delivery is not their primary task, there's a lot that can go wrong. To prevent these issues, Flowmailer SMTP Relay makes sure: