Re: javascript dns look up

On Apr 28, 5:45 pm, steve <s...@xxxxxxx> wrote:

Has anyone come across a "hack" to do a dns look up via JS
I want to evaluate an email address against a server to see if it is valid ,
I'm 50 % of the way there but i need a way to look up the email servers MX
record.

You may be wasting your time.

Many ISPs reject all outbound SMTP traffic, except to their own
outgoing mailserver. So you won't be able to establish an SMTP dialog
directly with the target user's mailserver.

Also, most mailservers no longer support the SMTP VRFY command - or
they seem to support it, but actually lie (eg. they say that *all*
addresses are valid). Your only remaining possibility is to check the
response to a dummy RCPT TO command - but I'm not sure that even this
is reliable now.

Try picking a relevant user's mailserver (not your ISP's outgoing
mailserver), and use Telnet to test the process manually. For example:

telnet mail.blah.com 25
HELO me
VRFY someuser
MAIL FROM me
RCPT TO someuser
(or somesuch)

If you cann't get it to work via Telnet, you won't be able to program
it - in Javascript or anything else.

HTH,
TC (MVP MSAccess)
http://tc2.atspace.com

.

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