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Free Email Port Checker

Free

Free email port checker — test your email server connectivity, authentication, and TLS configuration instantly. No account required.

Often Blocked
25
Standard SMTPSMTP
None / STARTTLS

The original standard email SMTP port. Mostly used for SMTP relaying between mail servers. Today, almost all consumer ISPs and cloud hosting providers block outbound traffic on port 25 to prevent spam.

Do not use for client submission. Only use for server-to-server relaying if your host permits it.
Recommended
587
Message SubmissionSMTP
STARTTLS

The standard port for SMTP message submission. It ensures that emails are submitted securely using TLS encryption (via the STARTTLS command) and requires proper authentication.

Highly recommended for all modern email clients sending mail to an SMTP server.
465
Secure SMTPSMTPS
Implicit SSL/TLS

Originally registered for SMTPS, then deprecated, and recently revived. It requires an implicit SSL/TLS connection before any SMTP commands are sent.

Use if your application requires implicit SSL/TLS instead of STARTTLS.
Recommended
993
Secure IMAPIMAPS
Implicit SSL/TLS

The standard port for receiving email securely via IMAP. It keeps your email client in sync with the server.

Highly recommended for reading emails.
143
Standard IMAPIMAP
None / STARTTLS

The default unencrypted port for IMAP. While it can be secured with STARTTLS, port 993 is generally preferred.

Avoid unless required by legacy systems.
995
Secure POP3POP3S
Implicit SSL/TLS

The secure port for POP3, which downloads emails to your local device and typically deletes them from the server.

Use if you strictly need POP3 instead of IMAP.
110
Standard POP3POP3
None / STARTTLS

The default unencrypted port for POP3.

Avoid unless required by legacy systems.

Frequently Asked Questions

What is the Email Port Checker tool used for?

The Email Port Checker tool tests your email server configuration by attempting a real connection to the specified SMTP, IMAP, or POP3 server. It checks connectivity on standard ports (25, 465, 587, 993, 995), verifies STARTTLS or SSL/TLS support, tests authentication, and reports any connection errors. This is essential for troubleshooting email sending failures, verifying hosting provider configuration, and auditing server security.

What SMTP ports should I use and when?

Port 25 is the original SMTP port for server-to-server mail transfer — most ISPs block outbound port 25 for clients. Port 587 (STARTTLS) is the recommended port for email client submission — it starts unencrypted then upgrades to TLS. Port 465 (SMTPS) uses SSL from the start and is supported by most modern clients. Avoid port 25 for sending from applications; use 587 with STARTTLS or 465 with SSL for all authenticated sending.

Why is my SMTP connection being refused?

SMTP connection refused errors are commonly caused by: (1) Wrong server hostname or port — double check your email provider's settings. (2) Firewall blocking the port on your server or network. (3) The mail service is down. (4) Your IP is blacklisted and the server is rejecting connections. (5) TLS/SSL mismatch between client and server settings. Use our SMTP Tester to narrow down which step fails.

What is the difference between SMTP, IMAP, and POP3?

SMTP (Simple Mail Transfer Protocol) handles sending and delivering email between servers. IMAP (Internet Message Access Protocol) is used by email clients to retrieve and sync messages from a mail server while leaving them on the server — ideal for multi-device access. POP3 (Post Office Protocol 3) downloads messages to the local device and typically removes them from the server. Most modern email clients and apps use IMAP. Use our IMAP Tester or POP3 Tester to verify server connectivity.

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