SMTP - OpenSRE Documentation

Overview

OpenSRE can send email through any existing SMTP relay you already use. You do not need to run your own mail server. Typical providers:

Google Workspace / Gmail SMTP
Microsoft 365 SMTP
AWS SES SMTP
SendGrid / Postmark / Mailgun SMTP
local dev SMTP sinks like Mailpit or MailHog

Prerequisites

An SMTP host you can reach from OpenSRE
A sender address the relay will accept
Optional username/password if the relay requires auth

Setup

Option 1: CLI wizard

opensre integrations setup smtp

You’ll be prompted for:

SMTP host
SMTP port
security mode: starttls, ssl, or none
optional username/password
sender address
optional default recipient

SMTP is configured separately from first-run onboarding — use this setup command.

Option 2: Environment variables

SMTP_HOST=smtp.example.com
SMTP_PORT=587
SMTP_SECURITY=starttls
SMTP_USERNAME=mailer
SMTP_PASSWORD=secret
SMTP_FROM_ADDRESS=opensre@example.com
SMTP_DEFAULT_TO=team@example.com

Variable	Default	Description
`SMTP_HOST`	—	SMTP hostname
`SMTP_PORT`	`587`	SMTP port
`SMTP_SECURITY`	`starttls`	`starttls`, `ssl`, or `none`
`SMTP_USERNAME`	—	Optional auth username (set with password)
`SMTP_PASSWORD`	—	Optional auth password (set with username)
`SMTP_FROM_ADDRESS`	—	Sender address
`SMTP_DEFAULT_TO`	—	Default recipient for outbound email

If authentication is required, set both SMTP_USERNAME and SMTP_PASSWORD.

Credentials

Use any SMTP relay your org already trusts. For local testing, Mailpit is a good fake SMTP target:

docker run -p 1025:1025 -p 8025:8025 axllent/mailpit

SMTP_HOST=localhost
SMTP_PORT=1025
SMTP_SECURITY=none
SMTP_FROM_ADDRESS=opensre@example.com
SMTP_DEFAULT_TO=team@example.com

Verify

opensre integrations verify smtp

A passing verification confirms OpenSRE can:

connect to the SMTP server
negotiate TLS when configured
authenticate when credentials are provided

Sample success output:

smtp: passed — Connected to SMTP server successfully.

Troubleshooting

Detail	Likely cause
`Missing recipient email address`	No `SMTP_DEFAULT_TO` is configured yet.
`username and password must both be set`	Only one auth field was provided.
`from_address must look like an email address`	Sender address is malformed.
`SMTP connection failed`	Host/port/TLS settings are wrong, or the relay is unreachable.

Security

Prefer app passwords / SMTP credentials scoped to a mailer account.
Store passwords in .env or your secret manager — not in source control.
Use starttls or ssl in production; reserve none for local sinks.

​Overview

​Prerequisites

​Setup

​Option 1: CLI wizard

​Option 2: Environment variables

​Credentials

​Verify

​Troubleshooting

​Security