Lettr

What Lettr is

Lettr calls itself "The email platform built for SaaS". It puts two products on one account: transactional email, sent from your application through a REST API or SMTP relay and billed per email, and marketing email, sent as campaigns to lists and segments and billed per contact. A third piece, an inbound email API, receives mail and passes it to your application as JSON. The homepage sums up the idea as one drag-and-drop editor for every email, transactional via API and marketing via campaigns, "One platform, one bill." The company says the platform is EU-hosted and GDPR and CCPA compliant, and that it is part of the Big Good group. Both products start with a free tier that needs no credit card.

The developer side

Lettr's developer path has six steps on the homepage, and they describe the transactional product well. You send your first email with a single API call, or swap your SMTP credentials into an existing setup without code changes. A Laravel package installs with one command, and official SDKs cover PHP, Node.js, Go, Java and Rust, all typed and documented. Authentication is handled by a step-by-step DNS wizard for SPF, DKIM and DMARC, and custom tracking domains are included on every plan. Webhooks report each email as delivered, opened, clicked or bounced, so you can sync your database or trigger in-app flows, and searchable logs give full-text search across every email sent with filters for recipient, status and tag.

The documentation adds the parts developers usually go looking for. Lettr generates and signs DKIM keys automatically once you publish the DNS records it provides, processes bounces, manages suppression lists and receives feedback loop reports from major mailbox providers, surfacing the results through webhooks and the dashboard. It sends from pools of IPs with established reputations. The knowledge base has DNS setup guides for hosts such as Cloudflare, AWS Route 53, GoDaddy, Namecheap, Hetzner, IONOS, Strato and Vercel, and articles on warm-up, suppression lists, BIMI, CAN-SPAM, CASL and Google and Yahoo sender requirements. A status page, an API reference, a changelog and an MCP server round out the developer resources.

The homepage lists the emails a SaaS product typically sends and shows each one in Lettr: onboarding sequences, password resets and login codes, trial expiry and upgrade nudges, usage alerts and billing notices, product updates and changelogs, and feature announcements targeted by usage.

The editor and campaigns

The shared editor is the part that sets Lettr apart from a pure sending API. It is a drag-and-drop builder powered by Topol, which the homepage says is used by more than 40,000 companies. Blocks include text, images, buttons, dividers, spacers, social links, video, raw HTML and loops. Around the editor sit synced sections (edit a header or footer once and it updates across all templates), a draft, review and publish workflow with approval, multilingual templates, dynamic placeholders such as a first name or plan name, and a SaaS template library with welcome, password reset, invoice, trial ending, changelog and usage alert templates. The point, in the company's words, is that marketing and product teams can work independently so that nobody files a ticket to change a button color.

Campaigns use the same account. You sync contacts from your product, build lists and segments by plan, activity or any property, and schedule and send as many campaigns as you need, since marketing is billed on audience size rather than volume. Multilingual campaigns, the newest feature on the homepage, send each contact the email in their own language. Lettr says SPF, DKIM and DMARC are handled for campaigns too, with reputation monitoring and warm-up, real-time logs and unified analytics across both kinds of email.

Inbound email

The inbound email API turns incoming mail into webhook calls. You add an inbound route for a domain or subdomain such as inbound.yourdomain.com, add the MX records Lettr shows you, and give it an HTTPS endpoint. Each message is received, validated and parsed into JSON with sender, recipients, subject, plain text and HTML bodies, full headers and attachments with filename, type, size and a secure download URL. Webhooks are credential-verified so you know each POST came from Lettr, and received messages appear in the same searchable logs as your sends. Routing works by address, subdomain or variable patterns such as reply+ticket_42@, and the Message-ID and In-Reply-To headers let you thread replies back to the right conversation. Lettr suggests email-to-ticket support, reply handling, email-to-app workflows, CRM sync and shared inboxes such as sales@ or billing@ run by code.

Plans and prices

The homepage prices both products in dollars. Transactional email starts at $0 a month with 3,000 emails every month free and scales up from $15 a month; marketing email starts at $0 for up to 500 contacts and scales up from $10 a month. Bundling the two earns a discount.

The transactional plan cards on the inbound page give the detail:

• Free: $0, 3,000 emails a month with a limit of 100 a day, 1 sending domain, email API and SMTP, basic analytics and 7-day data retention.
• Pro: $15 a month for 50K emails, then $0.80 per 1,000 extra, up to 10 sending domains, 1 inbound route, up to 10 webhook endpoints, no daily sending limit, advanced analytics and 30-day retention. The card states that Pro has no dedicated IPs.
• Business: $110 a month for 200K emails, then $0.80 per 1,000 extra, unlimited sending domains, 10 inbound routes, unlimited webhook endpoints, dedicated IPs as an add-on, priority support, a dedicated account manager and deliverability consultation.
• Enterprise: quoted by sales, with unlimited emails, dedicated IPs, an SLA guarantee, SSO/SAML, a dedicated account manager and 90-day data retention.

A volume selector runs from 3K to 2M+ emails a month. For help choosing, or for a migration from another provider, the site offers a call with its team.

Who it suits

Lettr suits SaaS companies that send both product email and marketing email and are tired of running them through two vendors. Developers get the API, SMTP, typed SDKs, webhooks and logs; product and marketing teams get an editor with approvals, synced sections and multilingual templates they can use without engineering. A startup can run on the free tiers, and the Pro step at $15 opens up no daily limit and 10 sending domains. Teams building support tools or reply handling get inbound parsing on the same account.

Its limits follow from its focus. Dedicated IPs start at the Business plan as an add-on, and SSO and an SLA sit at Enterprise, so larger senders with those needs should budget for the upper tiers. For a SaaS team that wants transactional and marketing email in one place with a real visual editor, Lettr covers the whole path from API call to campaign.