In my windows machine telnet services are set disabled in windows machine. But when you do:

telnet localhost 25 still the SMTP listens. how can i set not to listen to the service?

  • 2
    telnet localhost 25 != telnet localhost Dec 15, 2010 at 21:38
  • Seriously though, stop and/or disable the SMTP service... Dec 15, 2010 at 21:40
  • 2
    Please go review some of your older questions. If a valid answer is present then accept it, if not then add comments and/or update your questions to make it clear why you haven't accepted an answer.
    – Zoredache
    Dec 16, 2010 at 0:53

2 Answers 2


Port 25 is not the telnet port. It is the SMTP port, and what you're getting is the response from the SMTP server — as you say, "still the SMTP listens".

When you are using the telnet client this way, you are not actually using the telnet protocol. You're using the same command, but conveniently, unless you connect to something that starts sending the special telnet control character (0xFF in hex), it effectively acts like a raw TCP connection. (Give or take some technical quibbles — if the quibbles matter, use netcat instead of telnet.) And then, if you like, since SMTP is a simple protocol, you can type SMTP commands and pretend you are a mail program. (This can be quite useful for testing.)

So, basically, if you want this to stop, turn off SMTP. Otherwise, don't worry about it.


Port 25 is email not telnet, if you're running a mail server on that box you cant disable it. If you aren't running a mail server on the box then you just have to find whatever product has gotten installed that is listening on port 25.


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