How do I tell if my ISP is blocking my outgoing mail?

It is becoming more common that ISPs are blocking port 25 (SMTP port) forcing you to use their SMTP server. To see if you are blocked:

  1. Click Start Button (Windows Desktop)
  2. Click Run
  3. Enter "telnet"
  4. Enter "open mail.domain.com:25"

If you see a message like:

220 www.domain.com ESMTP

Then you are not blocked. If you can't connect, you are blocked. You should change your port to 26.

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