This free SMTP Test, Diagnostic, & Monitoring Tool enables you to easily troubleshoot and test SMTP connections without telnet. It supports both open and secure (SSL) SMTP server connections and contains a built-in library of commands such as EHLO, DATA, RCPT TO, etc…

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Common Causes of SMTP Server Connection Issues

1) Antivirus Software is Breaking Your SMTP Server Connection

Your antivirus software could be causing your SMTP connection issues. Solution: try disabling the software and connect to your SMTP relay server again. If this does not work, then move to the next cause.

2) Firewall Blocking Your SMTP Connection

A firewall can also be a common cause of SMTP connection issues. Solution: Try disabling your firewalls then reconnecting. If that works, it means that you need to update your firewall settings.

ISP Restriction

If the issue is not caused by your SMTP conenction or by antirvirus software, then check that your ISP allows for SMTP transmission your poart. Example: You’re using Port 25 and your ISP is blocking Port 25, try sending over Port 2525 or 587.

4) Deeper Issues (Use our SMTP Diagnostics Tool)

If the issue does not appear to be related to your ISP, antirvius software, or firewall, then there could be a deeper issue with your application. Try using our SMTP test tool to help diagnose the issue.

Get Rid of Your SMTP Issues — Use SocketLabs’ Cloud SMTP Relay Service

SocketLabs’ SMTP relay service technology is designed to make email delivery simple and effective. That means less headaches and more email reaching the inbox. Learn more about our SMTP relay service.