Client: Wren Relay, an email delivery service for businesses.
Wren Relay set out to give small and mid-sized companies the same deliverability the big senders enjoy, without running their own mail servers. Black River designed and built the platform end to end: a horizontally scalable cluster of mail transfer agents behind an authenticated SMTP relay and a REST API, per-customer sending domains with guided SPF, DKIM and DMARC setup, shared and dedicated IP pools, and automatic IP warm-up schedules that ramp volume safely for new senders.
Deliverability is protected around the clock: inbound bounces and ISP feedback-loop complaints are parsed and classified in real time, offending addresses go straight onto per-account suppression lists, and throttling rules adapt sending speed to each mailbox provider. Customers get open and click tracking, webhooks for every delivery event and a dashboard with reputation alerts. The platform grew to tens of millions of messages a month across hundreds of client accounts.
Services: SMTP Relay & Email API · Mail Server Setup · Deliverability & Reputation Management · Bounce & Complaint Processing · Multi-Tenant SaaS Platform