Free Email Deliverability Tools

Diagnosing a delivery problem in order

When mail is not arriving, the temptation is to change everything at once. It is faster to work through the layers in sequence, because each one rules out a whole category of cause. These tools map onto that sequence.

Start with transport: can anything reach the server at all? The SMTP server test answers that in one request, and distinguishes a firewall drop from a closed port. If the greeting arrives, transport is fine and you can stop looking at network configuration.

Then reputation: does the receiving world already distrust your IP? The blacklist checker queries dozens of DNSBL registries and groups the answers by how much each one actually affects delivery, so a listing on an obscure advisory list does not send you chasing a non-problem.

Then authentication: can receivers prove the mail is yours? The SPF, DKIM and DMARC checker shows what is published today and what to change. If records are missing entirely, the DNS record generator produces a correct starting set for your sending host.

Finally list quality: are you mailing addresses that exist? The email validator checks an address for syntax errors, provider typos, disposable domains, role mailboxes and missing MX records — the four things that generate most of a typical bounce rate.

Why these are free

Each of these tools is a single-target version of something PMTAcore does in bulk. The logic is the same code path; what the desktop app adds is scale and memory. It validates entire CSV lists with live SMTP verification and catch-all detection, checks every IP across every server you manage with results streaming in, creates DNS records through your provider's API as part of installing PowerMTA, and keeps a history of every check so you can see when something changed.

If the single-target versions are useful, the bulk versions probably will be too. See all features, compare pricing, or start on the free trial.