What is a relay service?

A relay service accepts email from your systems and forwards it to recipient servers. It's an intermediary that adds deliverability benefits without requiring you to manage sending infrastructure directly.

Relays provide: established IP reputation, proper authentication configuration, delivery optimization, bounce handling, and compliance with MBP requirements. Your application sends to the relay; the relay handles everything else.

Use relays when: your application sends email but you don't want to manage mail servers, you need better deliverability than direct sending provides, or you want to separate email infrastructure from application infrastructure. Most SMTP providers function as relay services.