What is senlo?

Senlo is an open-source email platform you host yourself for sending transactional and lifecycle messages. It gives developers a visual MJML-based drag-and-drop editor to build responsive templates, a REST API to trigger emails and manage contacts, and automation flows that can branch based on calls to your own APIs. Features include template versioning, multi-project isolation, real-time analytics with open/click tracking, and support for multiple delivery providers — Resend, Postmark, AWS SES, Mailgun, or any SMTP server. The stack runs via Docker Compose with bundled PostgreSQL and Redis, configured entirely through environment variables. The project is in MVP stage with a public roadmap that lists dark mode, a visual automation builder, and expanded provider webhooks as upcoming work.

Should you self-host senlo?

senlo scores 38/100 on selfhost.directory (how scoring works) and ranks #88 of 106 in Email. It has 178 GitHub stars.

There was no stable release in the past 12 months, so check the repository's recent activity before you rely on it.

Setup is moderate: expect some configuration beyond a single command. It is AGPL-3.0-licensed and written mostly in Typescript.

Its closest alternative on selfhost.directory is Postal (72/100, 16 899 stars). It scores higher overall, so compare the two before you pick. See senlo vs Postal side by side.

Features

Advanced Analytics
Conditional Content
Dynamic personalization
Dynamic Subjects
Email Analytics & Tracking
Email automations
Embedded Editor
GitHub OAuth
Multi-Project Isolation
Provider-Agnostic Delivery
REST API
S3-compatible Storage
Template versioning
Visual Drag-and-Drop Email Editor

How to configure senlo

ALLOW_REGISTRATIONtrueSet to "false" to close public registration. Existing users still sign in.
Set to "false" to close public registration. Existing users still sign in.
values: true, false
APP_URLhttp://localhost:3000The address Senlo is reached at, including the port if not 80/443. Links in outgoing mail point here.
The address Senlo is reached at, including the port if not 80/443. Links in outgoing mail point here.
AUTH_SECRETSigns sessions, and unsubscribe and tracking links in outgoing mail. Generate with: openssl rand -base64 32
Signs sessions, and unsubscribe and tracking links in outgoing mail. Generate with: openssl rand -base64 32
AUTH_TRUST_HOSTtrueTrust the host header (required behind most VPS setups)
Trust the host header (required behind most VPS setups)
DATABASE_URLpostgresql://senlo_user:senlo_password@db:5432/senlo_dbPostgreSQL connection string
PostgreSQL connection string
DEFAULT_FROM_EMAILSender for triggers and campaigns that do not set one
Sender for triggers and campaigns that do not set one
GITHUB_IDGitHub OAuth client ID for GitHub sign-in
GitHub OAuth client ID for GitHub sign-in
GITHUB_SECRETGitHub OAuth client secret for GitHub sign-in
GitHub OAuth client secret for GitHub sign-in
IS_DEMO_MODEfalseOnly for the public demo instance: shows the demo banner and loads Umami analytics
Only for the public demo instance: shows the demo banner and loads Umami analytics
values: true, false
LINK_SIGNING_SECRETSigns unsubscribe and tracking links instead of AUTH_SECRET. Set to rotate AUTH_SECRET without breaking links in mail already sent.
Signs unsubscribe and tracking links instead of AUTH_SECRET. Set to rotate AUTH_SECRET without breaking links in mail already sent.
REDIS_QUEUE_PREFIXsenloPrefix for queue and rate-limit keys if several instances share one Redis
Prefix for queue and rate-limit keys if several instances share one Redis
REDIS_URLredis://redis:6379Redis connection string for queues and rate limiting
Redis connection string for queues and rate limiting
S3_ACCESS_KEY_IDS3 access key ID
S3 access key ID
S3_BUCKETS3 bucket name
S3 bucket name
S3_ENDPOINTS3 endpoint URL (required for S3-compatible services like Cloudflare R2, MinIO)
S3 endpoint URL (required for S3-compatible services like Cloudflare R2, MinIO)
S3_FORCE_PATH_STYLEtrueForce path-style S3 URLs
Force path-style S3 URLs
values: true, false
S3_KEY_PREFIXuploadsPrefix for S3 keys
Prefix for S3 keys
S3_PUBLIC_URLPublic URL for S3 files (required when using S3_ENDPOINT)
Public URL for S3 files (required when using S3_ENDPOINT)
S3_REGIONautoS3 region
S3 region
S3_SECRET_ACCESS_KEYS3 secret access key
S3 secret access key
SECRETS_KEYEncrypts provider credentials (API keys, SMTP passwords) in the database. Falls back to LINK_SIGNING_SECRET / AUTH_SECRET.
Encrypts provider credentials (API keys, SMTP passwords) in the database. Falls back to LINK_SIGNING_SECRET / AUTH_SECRET.
STORAGE_DRIVERWhere uploaded images go. Default: the app's own disk. Set to "s3" for S3-compatible storage (Cloudflare R2, MinIO)
Where uploaded images go. Default: the app's own disk. Set to "s3" for S3-compatible storage (Cloudflare R2, MinIO)
values: s3
UMAMI_WEBSITE_IDUmami analytics website ID
Umami analytics website ID