Lettr is a transactional email platform for teams that want reliable sending without building and maintaining email infrastructure. Send via HTTP API or SMTP relay, track delivery and engagement with real-time events (delivered, bounced, delayed, opened, clicked), and debug issues with searchable logs and webhooks. Lettr is focused purely on transactional email; it does not support bulk sending or contact list imports, which keeps deliverability high and the platform focused. Lettr bridges the gap between developer and non-developer teams. Developers integrate once via API or SMTP, then product, design, and marketing teams can manage transactional templates independently using a visual drag-and-drop editor with version history and a draft/publish workflow, so routine copy and design edits never require dev tickets or redeploys. For teams migrating from another provider, Lettr is designed to make the switch straightforward: existing HTML templates can be imported directly, and Laravel teams can be up and running with a one-command setup. The template editor supports dynamic placeholders, HTML import (including React Email output), and multi-language templates. A synced sections feature lets teams update a shared header or footer once and automatically propagate changes across all templates that use it. Part of what sets Lettr apart from most transactional email platforms is its domain controls. Rather than sharing vendor infrastructure for tracking links and hosted assets, teams can configure their own custom tracking domain and custom storage domain, keeping all email touchpoints on-brand and under their own deliverability control. Standard sending domain configuration (CNAME, DKIM, DMARC) and inbound domain support are also included. Enterprise options extend this further with dedicated IP pools and custom rate limits for high-volume senders.