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ToolsEmail & DeliverabilitySMTP Test
Email & Deliverability

SMTP Test

Open an SMTP conversation, capture the greeting banner and enumerate advertised ESMTP capabilities.

Enter a value above and run the check to see results here.

How it works

Open an SMTP conversation, capture the greeting banner and enumerate advertised ESMTP capabilities.

Related tools

SPF LookupDKIM LookupDMARC LookupDMARC Generator

Frequently asked questions

Is the SMTP Test tool free to use?+

Yes. The SMTP Test runs directly in NetInsight with no signup required. Usage is rate limited per IP address to keep the service fast for everyone.

Are my queries logged?+

Diagnostic inputs are processed to produce your result and are not sold or shared. See our Privacy Policy for full detail on retention.

How accurate are the SMTP Test results?+

Results are fetched live from authoritative sources each time you run a check, so they reflect the current state rather than a cached snapshot.

More Email & Deliverability tools

Email & Deliverability

SPF Lookup

Fetch and parse a domain's SPF record.

Email & Deliverability

DKIM Lookup

Retrieve a DKIM public key by selector.

Email & Deliverability

DMARC Lookup

Read and interpret a DMARC policy.

Email & Deliverability

DMARC Generator

Build a valid DMARC record interactively.