Cannot Telnet (port 25) to select domain names from Exchange server.

Posted on 2009-02-15
Last Modified: 2012-05-06
We run a Windows server 2003 shop with exchange 2003.
Recently we began receiving delay notifications from our exchange server, after investigating  some of these domain names I noticed that I could not telnet into the mail server.  98% of email works just fine, but on a few select domains... I can't telnet to the mail server?  The telnet session appears to connect, but just sits there with a blank sreen.

For example:
We received the following NDR from our exchange box...

Your message did not reach some or all of the intended recipients.

      Subject:      RE: new e mail account
      Sent:      2/12/2009 8:41 AM

The following recipient(s) cannot be reached:

      'Jasper Darson ' on 2/14/2009 7:57 AM
            Could not deliver the message in the time limit specified.  Please retry or contact your administrator.
            < #4.4.7>

After doing a  MX nslookup for the associated domain name (set q=mx).

I get a mail server of  When I attempt to connect via telnet the session just goes blank and hangs?

I can connect to this mail server from home, we just can't do it from work?  Could our IP be blocked on th recipient end?
Question by:sna1alm
    LVL 4

    Assisted Solution

    go to and run their blacklisting check. It will take a few minutes to do and will give you a good indication of how your server is configured. If you are listed on the blacklist database and need any help with anything let me know!

    LVL 65

    Assisted Solution

    If you are then you are not blacklisted, but your IP address has a reverse DNS which would cause you to get blocked from some locations.

    If you are getting a flashing cursor then that means the connection cannot be made. Try a tracert to the host and see if the traffic is dropping somewhere - it could be a routing issue.

    LVL 17

    Accepted Solution

    If you are not able to telnet and get their banner that means they are not accepting your connection.
    I am sure they have blacklisted you. Enable NCSA Log on the default smap virtual server..
    restart the smtp service...
    then try to send a mail..
    now then go to start--> run--> logfiles... there you will get the ncsa log..
    open that log file.. it will show you the exact error.. who is terminating the connection.. why.. etc...

    You can attach that log here.. i can guide u better...
    let me know if you have any Questions


    Author Closing Comment

    Turned out to be a routig problem.  Sorry for the delayed response!  I forgot about it!  

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