MailSlurp vs MailTester

MailSlurp provides tools to build, test, and automate email and SMS workflows. Users can create temporary or permanent inboxes and handle messages through APIs, SDKs, SMTP, IMAP, and webhooks. It supports end-to-end tests for scenarios including OTP, MFA, magic links, and load testing, as well as device previews, email audits, and inbox placement checks. Pipelines can route messages and attachments using webhooks, forwarding, and automatic replies. AI extraction can turn emails and attachments such as PDFs and images into structured JSON using prompts, schemas, and OCR. Listed integrations include Playwright, Cypress, Selenium, HubSpot, Braze, Mailchimp, Zapier, and AI assistants through MCP. A REST API and official SDKs cover several programming languages. The free plan has capped allowances, including 500 received emails and 1,000 sandbox sends per month. Starter costs $19.99/mo; custom domains and phone numbers require Pro on Free and Starter plans. MailSlurp is web- and API-accessible.

MailTester checks why email may reach spam and returns a deliverability score out of 10. To run a test, generate a disposable address, send the message there and receive a report in seconds. Scoring starts at 10, subtracts points for detected issues, and explains penalties with suggested fixes. Authentication checks include SPF, DKIM, DMARC, domain alignment, reverse DNS and forward-confirmed reverse DNS. Sending IPs are checked against Spamhaus, SpamCop, Barracuda and other DNS blocklists. Content analysis covers HTML, text-to-image ratio, links, subject, List-Unsubscribe and Message-ID. Rspamd supplies a spam score and triggered rules. Newsletter checks include one-click List-Unsubscribe under RFC 8058, message size and text-image ratio. MailTester offers web, API and self-hosted platforms. Its API creates test addresses and reads report status and scores as JSON. The free plan costs nothing, needs no account and provides 25+ checks per test.