SMTP Labs vs testmail.app

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.

testmail.app receives, parses, spam-tests, and indexes test emails for automated end-to-end testing. Messages sent to addresses such as `{namespace}.{tag}@inbox.testmail.app` are routed into mailboxes, allowing tests to create addresses and mailboxes dynamically. The service provides simple JSON and GraphQL APIs, with client examples for JavaScript, PHP, Ruby, Python, Go, Bash, C#, and Java. Search includes wildcard queries, live waits for new mail, sorting, pagination, attachments, and SpamAssassin reports. GraphQL adds advanced filters, field selection, and custom sorting unavailable in the simple JSON API. Documented integrations cover Cypress, Selenium, TestCafe, and email OTP testing. New accounts receive a 14-day trial without a credit card, then move to the free plan. Free includes 100 emails monthly and one-day retention. Paid plans start at $9/mo (annual). Hosting uses AWS, with encrypted data and passwordless logins.