Emailens vs SMTP Labs
Emailens
emailens.devSMTP Labs
smtp.devSide by side
| Figure | Emailens | SMTP Labs |
|---|---|---|
| Price from | $9/mo | $7/mo |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | Yes | — |
| Web | Yes | Yes |
| API | Yes | Yes |
| Self-hosted | Yes | — |
| Plans published | 7 | 3 |
| Spec score · Email Testing Software | 9.4 (#1) | 8.4 (#8) |
| API authentication | Authenticated API calls use an ek_live bearer token or x-api-key header. | API requests use an X-API-KEY header, and newly created token values are shown only once. |
| Documentation depth | Documentation includes getting started, REST endpoints, MCP setup and tools, client reference, engine APIs, rate limits and GitHub Action guidance. | The site publishes API reference, setup pages, feature pages, CI and E2E guides, an llms.txt index, and markdown versions of documentation pages. |
| Integrations | The product offers a web app, REST API, MCP server, GitHub Action, and standalone @emailens/engine package. | The maker documents CI use with GitHub Actions, Jenkins, GitLab CI, and CircleCI, using standard SMTP and the REST API. |
| Purpose | Emailens previews and checks how HTML emails render across 21 email clients. | SMTP Labs is an email testing service that receives test email over SMTP and lets users inspect it through the web UI, IMAP, POP3, or API. |
| Support | The security page says vulnerability reports are acknowledged within 48 business hours. | The terms state the company has no support or maintenance obligation except as may be included in a paid subscription plan. |
| What it does | Emailens previews and audits HTML email rendering across 21 email clients, producing compatibility scores, warnings, dark-mode variants and screenshots. | SMTP Labs is a hosted email-testing sandbox where inbound messages can be inspected through a web interface, IMAP, POP3, or REST API. |
Plans
Emailens
- FreeFree
- FreeFree
- Dev$9 a month
- Dev$9 a month
- Pro$19 a month
- Pro$19 a month
- Team$49 a month
In their own words
Emailens
Emailens previews HTML email rendering across 21 email clients and checks compatibility across 298 CSS and HTML features. It scores compatibility from 0 to 100 per client and provides rendered screenshots and simulated dark mode variants. Inputs include HTML, React Email JSX, MJML, and Maizzle. Developers can use a web app, REST API, MCP server, GitHub Action, or standalone @emailens/engine package. Campaign HTML can be imported from a view-in-browser link; Mailchimp URL import is marked verified, while other listed platforms require pasted HTML. Emailens discusses merge tags for Mailchimp, Klaviyo, HubSpot, Braze, and Salesforce Marketing Cloud. The free plan costs nothing and includes 30 simulated previews per day, all 21 clients, one monitored domain, seven-day audit history, and three AI Fixes. Paid plans are Dev at $9 a month, Pro at $19 a month, and Team at $49 a month. Emailens says unsaved previews are processed in memory and authenticated previews and screenshots are purged after 30 days.
SMTP Labs
SMTP Labs is an email testing service that receives test messages over SMTP and lets you inspect them on the web, through IMAP or POP3, or via an API. Messages remain in a sandbox and cannot reach external recipients. Inspection includes HTML and plain text, headers, MIME structure, raw source, and attachments. SPF, DKIM, and DMARC checks appear in the interface and API, while a deliverability audit reviews sender configuration, HTML, links, and content patterns associated with spam filters. The REST API covers domains, accounts, mailboxes, messages, and tokens; server-sent events can push new messages. SMTP, IMAP, and POP3 work without a vendor SDK. The Lite plan is free at free with one domain, 50 accounts, and seven-day retention. Pro costs $7 a month, and Max costs $20 a month, with longer retention and expanded domains or accounts. Email and account data are primarily processed in the United States.