rail delivers your notifications, alerts and receipts straight to the recipient's mail server — DKIM-signed, retried on per-domain backoff. Replies, bounces and spam complaints come back to your app as webhooks. No mailbox to poll, no backend to run.
One connection, authenticated by client certificate. SMTP on port 465, an HTTPS API, or a plain HTML form posted straight from a static site — no backend in between.
rail resolves MX itself, signs with DKIM and hands the message to the recipient's server. A domain that is refusing mail gets backed off harder; one that recovers gets retried sooner.
Replies, bounces and spam complaints arrive on port 25, get matched back to the message that caused them, and POST to your webhook with the original message attached.
Pick whichever your service already speaks.
A service that already has an SMTP library keeps it. A service that would rather POST JSON does that instead. A static site with no backend at all points its contact form at a rail form target and gets the submission as email — with a honeypot, a per-token rate limit and a spam challenge in front of it.
Attachments are the fastest way to get a message rejected, and a mailbox keeps whatever you send forever. Hand the file to depot, put the expiring link in the mail, and rail sends a message that stays small enough to arrive.
Get a client certificate, point your service at smtp.ataca.io, and rail takes it from there. The dashboard shows you every message it handled.