MOO-cows Mailing List Archive


Re: E-Mail Adresses

At 06:08 PM 21/01/96 PST, Matt Pauker wrote:

>You could just finger the user - Connect to port 79 of the domain (In this
>case, and just send the username (david).  If you get anything
>other than:
>finger: <username>: no such user
>Then the email is valid.

I'm afraid that's not very general because:
* lots of people use aliases (like First.Last@host) instead of usernames,
* lots of email addresses have no hostname (like First.Last@domain)
  and domain may not resolve to an IP address.

If you were going to try this it would probably be better
to use the SMTP VRFY command by doing something like
*  look up the MX records associated with the domain part.
    if you don't find it then try resolving the domain itself.
*  Open a connection to port 25 on host you have chosen.
*  Send the command VRFY <emailaddress>
*  check the numeric response code - 500's are good, 200's are bad

But be warned - some SMTP servers will say anything is fine.

I've used this technique for verifying large databases of email address
and it works pretty well - probably better than 90% can be
tested this way.

Guy Carpenter - Clearwater Technical Services
Tel: (070) 953309                  Fax: (070) 953007


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