Email testingHow to Test if a Mail Server Supports STARTTLS
3 min readVerify STARTTLS support with OpenSSL, interpret SMTP capability responses, and validate TLS/auth behavior safely before production rollout.
Read guideEmail testing, deliverability, and API guides
Build more reliable email and SMS workflows with practical MailSlurp tutorials, implementation guides, and production-ready testing advice.
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335 guides
Email testing
Email testingHow to send a test email in Mailchimp and preview it like a QA team
3 min readStep-by-step Mailchimp test email workflow with a QA checklist for links, personalization, rendering, spam risk, and inbox behavior.
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DeliverabilityFixing SMTP 550 Errors (550 5.1.1, Relay Denied, Policy Rejection)
4 min readDiagnose and fix SMTP 550 errors with a practical troubleshooting matrix for recipient issues, relay policy, auth setup, and sender reputation.
Read guideFake SMTP Server Setup for Testing (Local + CI Pattern)
3 min readSet up a fake SMTP server for testing, validate send flows safely, and move from local-only checks to production-grade CI email validation.
Read guideEverything You Need to Know About SMTP (Developer Guide)
3 min readLearn SMTP fundamentals, command flow, response code classes, port selection, and production checklists for reliable email delivery.
Read guideDomain reputation tools: what to monitor weekly and what to fix first
3 min readA practical guide to domain reputation tools for email teams, with a monitoring cadence and incident response framework.
Read guideBest Free Email Testing Tools in 2026: What to Use First
4 min readCompare free email testing tools for inbox workflows, free email rendering, spam checks, SPF/DKIM/DMARC validation, deliverability, and upgrade timing.
Read guideWhat Can You Do with MailSlurp Email Testing?
3 min readUse MailSlurp to automate inbox workflows, test OTP and transactional flows, validate deliverability signals, and ship safer releases.
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SMTP & APIsPHP mail() function: how to send email in PHP safely
3 min readLearn how to use the PHP mail() function, common failure modes, and when to switch to SMTP libraries for reliable production email delivery.
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MailSlurp guidesParse email data using AI
5 min readConvert product order email receipts into structured data using AI transformers
Read guideThe state of AI email parsing and transformation in 2025
20 min readHow OCR and AI can turn emails and file into structured actionable data. An overview of key concepts and players
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DeliverabilitySimulate soft and hard bounce email responses
3 min readTest mailserver responses using bounce simulation rules in MailSlurp
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