SMTP Labs
SMTP Labs is an email testing service for receiving test messages and inspecting them in a web interface, through IMAP or POP3, or with its API.
What SMTP Labs is
SMTP Labs is an email testing service for receiving test messages and inspecting them in a web interface, through IMAP or POP3, or with its API. Messages remain inside its sandbox, so they cannot reach external recipients. Users can examine HTML and plain text, headers, MIME structure, raw source, and attachments. The interface and API show SPF, DKIM, and DMARC checks, and a deliverability audit reviews sender settings, HTML structure, links, and content patterns that spam filters flag. Its REST API covers domains, accounts, mailboxes, messages, and tokens; server-sent events can push new messages as they arrive. SMTP, IMAP, and POP3 do not require a vendor SDK. The free Lite plan includes one domain, 50 accounts, and seven-day message retention. Pro costs $7 a month and Max costs $20 a month. Retention varies by plan, up to 90 days. Email and account information are primarily stored and processed in the United States.
Good
- Inspect messages through web, IMAP, POP3, or API.
- Checks SPF, DKIM, and DMARC.
- Supports custom domains, catch-all accounts, and plus aliases.
- New messages can be pushed through server-sent events.
Watch out
- Sandbox messages cannot reach external recipients.
- Lite retains messages for seven days.
- Full account deletion is unavailable.
- Support is not guaranteed except as included in paid plans.
Who it suits
SMTP Labs suits developers and teams who need to inspect test email without sending it to external recipients. Its documented CI integrations include GitHub Actions, Jenkins, GitLab CI, and CircleCI.
Verdict
SMTP Labs provides multiple ways to inspect test messages and check authentication and deliverability. Consider its retention limits, sandbox restriction, and account-deletion policy before adopting it.
Plans and prices
From SMTP Labs's own pricing page, checked 15 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Lite | Free | 1 domain · 50 accounts · 7-day message retention · SMTP, IMAP, POP3, API · email audit · monthly |
| Pro | $7 a month | 5 domains · 25,000 accounts · 30-day message retention · SMTP, IMAP, POP3, API · email audit · catch-all and aliasing · monthly |
| Max | $20 a month | Unlimited domains · unlimited accounts · 90-day message retention · SMTP, IMAP, POP3, API · email audit · catch-all and aliasing · monthly |
The facts
Each one read from SMTP Labs's own pages, with the date it was checked.
What it does
- Account deletion
- Users can request account deactivation, but full account deletion is unavailable because of anti-abuse obligations.checked 3 Oct 2026
- API and realtime
- The REST API covers domains, accounts, mailboxes, messages, and tokens; new messages can be pushed through server-sent events.checked 3 Oct 2026
- API authentication
- API requests use an X-API-KEY header, and newly created token values are shown only once.checked 15 Oct 2026
- API rate limit
- The documented limit is 4,096 requests per minute per authenticated user, with HTTP 429 responses when exceeded.checked 15 Oct 2026
- Authentication checks
- Every received message can show SPF, DKIM, and DMARC verification results in the interface and API.checked 15 Oct 2026
- Catch-all accounts
- A wildcard account can capture mail for otherwise uncreated addresses on a domain.checked 15 Oct 2026
- CI integrations
- Documentation provides examples for GitHub Actions, Jenkins, GitLab CI, and CircleCI using SMTP plus the REST API.checked 15 Oct 2026
- Client compatibility
- Thunderbird and Apple Mail can connect over IMAP, while webmail is available at webmail.smtp.dev.checked 15 Oct 2026
- Custom domains
- Users add domains or subdomains and point their MX records to mx.smtp.dev to receive test mail.checked 15 Oct 2026
- Data location
- The privacy policy says email content and account information are primarily stored and processed in the United States, with safeguards for international transfers.checked 15 Oct 2026
- Deliverability audit
- Its audit checks sender configuration, subject, HTML structure, links, images, and content patterns associated with spam filtering.checked 15 Oct 2026
- Documentation depth
- The site publishes API reference, setup pages, feature pages, CI and E2E guides, an llms.txt index, and markdown versions of documentation pages.checked 15 Oct 2026
- Domains and aliases
- Users can bring custom domains and subdomains, use catch-all accounts, and route plus-sign aliases.checked 3 Oct 2026
- End-to-end testing
- A Playwright guide demonstrates triggering a password reset, retrieving the email through the API, extracting its link, and completing the flow.checked 15 Oct 2026
- Independent article date
- SMTPedia published its smtp.dev assessment on 11 July 2026.checked 15 Oct 2026
- Independent classification
- SMTPedia classifies smtp.dev as a throwaway email provider and says it had tracked 361 rotating domains since approximately 2021.checked 15 Oct 2026
- Independent criticism: abuse patterns
- SMTPedia claims smtp.dev addresses appear in free-tier abuse, referral farming, crypto-airdrop sybil activity, and chargeback-fraud patterns.checked 15 Oct 2026
- Independent criticism: abuse risk
- SMTPedia says the provider's programmatic address creation and inbox polling indicate potential bot-grade abuse and recommends blocking or extra verification for its addresses.checked 15 Oct 2026
- Independent DNS finding
- DNSCheck.pro observed Cloudflare authoritative nameservers and an MX record pointing to mx.yandex.net for smtp.dev.checked 15 Oct 2026
- Independent DNS limit
- DNSCheck.pro reported that smtp.dev lacked a DMARC record at the time of its September 2025 scan.checked 15 Oct 2026
- Independent DNS report date
- DNSCheck.pro's report for smtp.dev was generated on 25 September 2025.checked 15 Oct 2026
- Independent mail test
- DNSCheck.pro's scan found the domain's mail server rejected [email protected] but accepted [email protected].checked 15 Oct 2026
- Integrations
- The maker documents CI use with GitHub Actions, Jenkins, GitLab CI, and CircleCI, using standard SMTP and the REST API.checked 3 Oct 2026
- Licence
- The terms grant a limited, revocable, non-transferable license for personal or internal business use and prohibit copying, reverse engineering, hosting, or commercial exploitation.checked 15 Oct 2026
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