Litmus

Litmus is the long-standing standard for previewing how a marketing or transactional email actually renders across Gmail, Outlook, Apple Mail, mobile clients, and dark-mode variants. Pre-send checklist catches broken links, missing alt text, spam triggers, image weight, and load time. Build, Proof, and Analytics modules cover authoring, review, and post-send heatmaps.

A SaaS product sends on behalf of its customers, so the deciding factors are tenant isolation, whether suppressions can be scoped rather than global, and whether support can answer why one specific account did not receive one specific email. Lifecycle automation and transactional sending usually need to coexist.

Against trial expiry notices, dunning, onboarding sequences, and per-tenant transactional mail, Litmus covers multi-tenant support and webhook coverage, and does not cover event stream, the suppressions API, and scheduling. Whether that gap matters depends on how central those are to the build.

• Multi-tenant: Yes
• Event stream: No
• Suppressions API: No
• Operating since: Not published
• Scheduling: No
• Best published rate per 1,000: Tiers not published in comparable form
• Deliverability: Not applicable; preview and QA, not a sender.
• Webhooks: Yes
• Starts at: Basic plan listed on the public pricing page; exact figure varies by region and is sales-driven on higher tiers

Not applicable; preview and QA, not a sender.

Marketing and lifecycle teams that need pixel-accurate previews across every major client before sending.

Solo developers sending only plain-text or simple transactional email.