How to check if a Email address exist or not using the command line

• In this example we will test for the Email address [email protected], replace the gmail Email address with the email address you want to test
• Open the command line/command promt and type in the following command

  nslookup -type=mx gmail.com

  This command will list the MX records of the gmail domain eg.

  Server:        10.0.2.2
   
  Address:    10.0.2.2#53
  
   
  Non-authoritative answer:
   
  gmail.com    mail exchanger = 5 gmail-smtp-in.l.google.com.
   
  gmail.com    mail exchanger = 10 alt1.gmail-smtp-in.l.google.com.
   
  gmail.com    mail exchanger = 20 alt2.gmail-smtp-in.l.google.com.
   
  gmail.com    mail exchanger = 30 alt3.gmail-smtp-in.l.google.com.
   
  gmail.com    mail exchanger = 40 alt4.gmail-smtp-in.l.google.com.
   
   
  Authoritative answers can be found from:
   
  alt1.gmail-smtp-in.l.google.com    internet address = 74.125.39.27
   
  alt3.gmail-smtp-in.l.google.com    internet address = 74.125.65.27
   
  alt4.gmail-smtp-in.l.google.com    internet address = 74.125.91.27
   
  alt2.gmail-smtp-in.l.google.com    internet address = 209.85.225.27
   
  gmail-smtp-in.l.google.com    internet address = 209.85.227.27

• Select one of the servers listed in the list of MX records and pretend to send a message to that server from your local machine
  • Connect to the server via telnet

    telnet alt1.gmail-smtp-in.l.google.com 25

  • Type in the HELO command

    HELO

  • Identify yourself using any email address eg. [email protected]

    mail from:<[email protected]>

  • Type in the email address that you wish to verify

    rcpt to:<[email protected]>

• After the last command entered, the server will respond with a message whether the email address exist/is valid or not e.g.

  250 2.1.5 OK o15si4900954fal.31 //For success

  and

  The email account that you tried to reach does not exist. //Failure