Custom SMTP

Custom SMTP connects any standards-compatible SMTP relay to Wodby without requiring a provider-specific integration. Use it with services such as OpenSMTPD when your mail provider is not listed separately in the provider catalog.

Setup fields

Field	Required	Relay variable	Description
Relay host	Yes	RELAY_HOST	Relay hostname without a URL scheme or port, for example smtp.example.com.
Relay port	No	RELAY_PORT	Relay TCP port. The default is 587.
Relay security	No	RELAY_PROTO	smtp+tls for mandatory STARTTLS or smtps for implicit TLS. The default is smtp+tls.
Username	No	RELAY_USER	Relay username. Omit it for relays that authenticate by network identity.
Password	No	RELAY_PASSWORD	Relay password, stored as a secret.

Custom SMTP intentionally supports encrypted relay modes only. Use smtp+tls for the usual submission service on port 587. Select smtps when the provider requires implicit TLS, commonly on port 465.

Attach to OpenSMTPD

1. Open the project or organization Integrations page and create a Custom SMTP integration.
2. Enter the relay host and any credentials required by the provider. Set the port and security mode when the provider does not use the defaults.
3. Open the app environment containing OpenSMTPD and select its OpenSMTPD service.
4. Attach the integration to Third-party SMTP server for Relay.
5. Redeploy the app environment so OpenSMTPD receives the relay configuration.

Applications continue to send mail to OpenSMTPD on its internal port 25. OpenSMTPD then forwards the message to the configured upstream relay.

The relay host is mandatory. Wodby rejects an incomplete Custom SMTP configuration rather than allowing OpenSMTPD to attempt direct delivery.

See OpenSMTPD for service usage and a test-message example.