Hyvor Relay

What Hyvor Relay is

Hyvor Relay is an open-source email API for developers, available as a hosted service or for self-hosting. Its REST API sends HTML and plain-text email, including attachments, custom headers, and messages to multiple recipients. The API supports idempotent requests, while scope-based tools can automate domain setup, suppressions, API keys, and webhooks. Event webhooks report deliveries, bounces, domain verifications, and other events in real time. Projects group domains, API keys, and webhooks; each project handles either transactional or distributional email, using separate IP pools for those types. Relay manages bounces, complaints, and suppressions, with searchable delivery logs retained for 30 days. It also supports inbound email, SMTP relay, and a dedicated IP option. Self-hosting uses PostgreSQL with Docker Compose or Docker Swarm, and deployment guidance covers single-server and multi-server setups. The self-hosted product is licensed under AGPL-3.0. Relay requires OpenID Connect authentication and does not include its own login or signup system. The free plan is available; Cloud Standard is listed at €30/month with 300,000 emails included, and additional volume costs €1 per 10,000 emails.

Who it suits

Relay suits developers who need an email API with automation, event webhooks, and delivery handling, especially teams that want to self-host. Teams planning newsletters should account for the lack of built-in newsletter management, and self-hosting requires PostgreSQL and Docker deployment.

Limits

The free plan's monthly sending limit is 300,000 emails. Cloud Standard includes 300,000 emails per month, with additional volume priced at €1 per 10,000 emails.

Getting started

1. Visit the Hyvor Relay website.
2. Choose the hosted service or follow the self-hosting guide.
3. For self-hosting, prepare PostgreSQL and deploy with Docker Compose or Docker Swarm.
4. Set up OpenID Connect authentication.
5. Create a project and configure its domains, API keys, and webhooks.
6. Choose transactional or distributional email for the project.

Verdict

Choose Hyvor Relay if you need a developer-focused email API with self-hosting, automation, and delivery event reporting. Look elsewhere if you need built-in newsletter management or want a project to send both transactional and distributional email.