TOOL / SMTP-DIAGNOSTIC
SMTP Diagnostic
Comprehensive mail server health check: MX records, reverse DNS, blacklists, SPF, DMARC, MTA-STS, and DANE/TLSA, with an overall score and prioritized fixes.
Raw SMTP connection tests (EHLO, STARTTLS capability banners) require direct TCP access on port 25 which is blocked by serverless platforms. This tool performs all DNS-observable checks and surfaces what can be diagnosed without a raw socket connection.
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