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nikolas.e

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Reply with quote  #1 
What is the best way to verify that a email address exist? I read about some sites that can  verify an email address for you but honestly i want to know if its still possible to do it via command prompt(Telnet) or there are restrictions now. NOTE: I tried use telnet but i failed miserable [smile]
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jsclmedave

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Reply with quote  #2 
In your environment?  Or outside in another company?
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cj_berlin

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Reply with quote  #3 
Hi,

if you need to verify an email address external to your own organization, the only reliable way is to send an email. The most you can do short of sending email and asking for confirmation is

  • verifying the domain is registered
  • verifying the domain has an MX record in DNS
  • verifying the server listed there is listening on 25/tcp

From there, your possibilities probably are less than limited. In a better, spam- and malware-free world you would then
  • connect to the MX on 25/tcp and issue a HELO you.com --> in this world, you won't get very far if your IP does not have a PTR resolving to that name
  • issue a MAIL FROM: you@you.com --> that's if you've got past the previous one which you probably haven't
  • issue a RCPT TO: she@them.com --> what you're hoping for is a NO SUCH RECIPIENT or OK but again, you've probably not got past HELO
  • hang up and just assume that OK=Mailbox exists and NOK=it doesn't
In this world, you could buy a spammer datasource but those aren't very reliable either.

What do you need this functionality for?

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donoli

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Reply with quote  #4 
At one time, you could verify an email user by telnet but it isn't reliable now.  You would telnet to the domain on port 25 & either run expn or vrfy command & the name. The response would tell you if it were valid or not.
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wobble_wobble

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Reply with quote  #5 
Easy tool to use...
SMTP Diag does a lot of the work.
https://www.microsoft.com/en-ie/download/details.aspx?id=11393

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nikolas.e

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Reply with quote  #6 
Hello,

Emails outside our  company environment like Gmail or Hotmail. I guess the easiest way is to sent an email asking for confirmation as Evgenij told or i could try use telnet again hopefully with better results


Joe i read about the tool : SmtpDiag is a troubleshooting tool designed to work directly on a Windows server with IIS/SMTP service enabled or with Exchange Server installed. Requires Exchange Server 2000-2003

We don't have exchange in our environment.


What do you need this functionality for?  Evgenij i dont i have been asked from the company if its possible. 





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wobble_wobble

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Reply with quote  #7 
Nikolas

No exchange server needed.
Mailing you an output.



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dennis-360ict

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Reply with quote  #8 
Nice cj! I knew most of it, but its nice to have a writeup like this, thanks for taking the time.
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donoli

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Reply with quote  #9 
cj, I thought those commands only checked if the SMTP server was acting as an opened relay.
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cj_berlin

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Reply with quote  #10 
Quote:
Originally Posted by donoli
cj, I thought those commands only checked if the SMTP server was acting as an opened relay.


It's standard SMTP protocol. If the recipient you specify with RCPT TO: is internal to the server you are talking to (which is what we're trying to establish here), it isn't a relay if it accepts your message.

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