Tag Archive for 'nslookup'

Check connectivity to a mail server

Published
by
admin
on June 4, 2008
in How to and Trouble shooting
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When email does not get delivered it can be a real pain.

Here I will try to explain a few basic trouble shooting tips that you can perform to try and narrow down the problem by connecting to the remote mail server.

I will be using Windows XP commands for this. But most operating systems have these tools inbuilt or very similar ones available.

Tools used

  • NSLOOKUP
  • PING
  • Telnet

NSLOOKUP

First off we will use NSLOOKUP to find the mail server we are having problems sending to.

  1. Open a command prompt.
  2. Type “NSLOOKUP” and press enter.
  3. Type “SET TYPE=MX” and press enter.
  4. Type in the domain name your having problems with eg. “microsoft.com” Look for the server name with the lowest MX preference number and note it down. If they are all the same preference, just use anyoneone.
  5. Quit NSLOOKUP by typing “exit”

PING

Now we will use the PING command to see if the server we found in part one is reachable.

  1. Open a command prompt.
  2. Type “PING server address” (ping mail.microsoft.com )

Please note that if the server has ping disabled you may get Request timed out message. This does not necessarily mean it is down.

TELNET

Lastly using the TELNET command we will connect the the remote email server and send a test email.

  1. Open a command prompt.
  2. Type “TELNET server address 25”
  3. You should see a server welcome message
  4. Type “HELO” and press enter (you might not see what you type. This is normal)
  5. Type “mail from: myemail@mydomain.com” substituting your address and press enter.
  6. Type “rcpt to: user@server.com” substituting the recipients address and press enter.
  7. Type “data” and press enter.
  8. Type “Subject: Test message” and press enter TWICE
  9. Type “This is a test message.” and press enter. You must have the . (full spot/period)
  10. Type “quit” and press enter to exit.

If everything has work the message will now be sent, confirming the server is working fine. If not more troubleshooting is required!