MailTest

MailTest evaluates email deliverability by performing twelve distinct checks, including SPF, DKIM, DMARC, blacklist status, SpamAssassin scoring, rDNS verification, BIMI presence, MTA‑STS, TLS‑RPT, ARC, content scoring, and inbox placement. The service presents the results of each check and explains the root cause of any failures, allowing users to apply targeted fixes. It also offers continuous domain health monitoring, scheduled tests, PDF reports, webhooks, and competitor intelligence, with an API for automation and a Docker‑based self‑hosted option.

The tool is aimed at developers and teams that send marketing or transactional emails and need to diagnose why messages land in spam folders. It integrates with common email providers and services such as Gmail, Outlook, AWS SES, SendGrid, Postmark, Mailchimp, HubSpot, Klaviyo, Mailgun, and SparkPost. A free tier is available without sign‑up, and the platform can be run locally via Docker.

MailTest’s distinctive feature is its root‑cause diagnosis: rather than merely indicating a failed authentication check, it details why the failure occurred and suggests specific remediation steps. This level of insight is intended to reduce the time spent troubleshooting deliverability issues and improve inbox placement rates.