SMTP Labs vs smtp4dev
SMTP Labs
smtp.devsmtp4dev
github.comSide by side
| Figure | SMTP Labs | smtp4dev |
|---|---|---|
| Price from | $7/mo | — |
| Free plan | Yes | — |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | — | Yes |
| macOS | — | Yes |
| Linux | — | Yes |
| API | Yes | Yes |
| Self-hosted | — | Yes |
| Plans published | 3 | 0 |
| Spec score · Email Testing Software | 8.4 (#8) | 7.2 (#23) |
| Message inspection | Messages can be viewed as HTML or plain text and examined as MIME structures, headers, attachments, or complete RFC 5322 source. | Features include SMTP session logs, multipart MIME inspection, HTML rendering, validation, and compatibility reports. |
| Purpose | 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. | smtp4dev is a fake SMTP server for development and testing, letting developers test email without sending it to real customers. |
Plans
In their own words
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.