Senlo

Senlo is a layer on top of the email delivery provider a team already uses, such as Resend, Postmark or any SMTP server. It gives you a visual editor for transactional email templates, with rows, columns, merge tags and conditions, and versions you can roll back to. Templates can be sent through a single API request, and developers receive the same template through the API without writing MJML by hand.

Lifecycle automations start from events sent to the API, such as a new contact being added. An automation can send an email, wait, check your own API whether a user did something, and then take a different path. Each node shows how many contacts are in it. Sends, deliveries, bounces and engagement are shown per workspace, with a live feed of failures and a suppression list. Senlo renders, personalises, tracks and decides, then hands each message to the provider you chose, so switching providers does not require editing templates.

The product suits teams that send transactional email and onboarding sequences and want editors who do not write code to work on them. It can be self-hosted with Docker Compose under the AGPL-3.0 license, or used as a hosted service with a free plan for one person, and paid plans that add members, roles and audit logs.