Test Your SMTP Connection With Confidence

Yes. The SMTP checker is completely free to use, with no signup or account required.

No. Your credentials are held in memory only for the single test you run, then discarded immediately. They are never written to disk, saved to a database, or recorded in any log.

Port 465 (implicit SSL/TLS), and ports 587 and 2525 (STARTTLS). Port 25 and plaintext connections are intentionally not supported — every test runs over TLS.

Not necessarily. A successful test confirms your server accepted the message for delivery. Whether it lands in the inbox or spam still depends on SPF, DKIM, DMARC, and your sending reputation.

The diagnostic log is sanitized on the server so credentials never leave it. The authentication step always appears as [REDACTED], and message contents are omitted.

A single fixed plain-text message with a timestamp and your host, port, and security settings. There is no custom content, HTML, attachments, CC, or BCC.

Common causes are an incorrect hostname or port, invalid credentials, a provider that requires an app-specific password, or a certificate that does not match the hostname. The result panel names the exact stage that failed.