RE: domain validation for e-mail addresses -- MIDRANGE-L

Just because it is interesting:

If you want to see MX records for a given host, and you don't have your own
copy of DIG (Unix, NT, etc.), go to
http://www.samspade.org/t/dig.cgi?a=us.ibm.com (this runs the DIG CGI script
at samspade.org, I am passing the us.ibm.com domain as an example a
parameter.)  There are lots of freeware/shareware tools that include
nslookup/dig/host functions for DOS/Win9x/NT/2K - including a free suite at
samspade.org.

There is an NSLOOKUP on OS/400 (I'm on V4R4), but it does not support MX
lookups.

-Gary Patterson

-----Original Message-----
From: owner-midrange-l@midrange.com
[mailto:owner-midrange-l@midrange.com]On Behalf Of Walden H. Leverich
Sent: Monday, September 11, 2000 10:34 AM
To: 'MIDRANGE-L@midrange.com'
Subject: RE: domain validation for e-mail addresses


Joel,

Let me throw a log on the fire here. You SHOULD be checking us.ibm.com
However, you need to look for MX records in the DNS structure, not A
records. Ping, tracert, web, ftp etc. all look for 'A' type records when
converting domain names to ip addresses. However, mail looks at MX, or Mail
eXchanger, records. If I lookup the 'A' records for us.ibm.com I don't get
any hits. However, if I lookup the MX records for us.ibm.com then I get 8
possible mail exchangers for that domain.

Validating the high-level domain (ibm.com) may not yield anything useful. In
many cases the high-level domain may not even have an IP address associated
with it.

Validating the domain of an e-mail address is not for the faint of heart,
but if you want to do it you'll be in DNS-land and I highly suggest you get
a copy of "BIND and DNS" which is the definitive subject on the matter.

Alternatively, export the e-mail addresses to a PC and use many of the
already written components available to check e-mail address there.

-Walden

-----Original Message-----
From: Joel Fritz [mailto:JFritz@sharperimage.com]
Sent: Thursday, September 07, 2000 4:34 PM
To: 'MIDRANGE-L@midrange.com'
Subject: RE: domain validation for e-mail addresses


Thanks to everyone for the clarification on what is a real domain.  I was
afraid of having to do more work. <g>

> -----Original Message-----
> From: Phil Groschwitz [mailto:sublime78ska@yahoo.com]
> Sent: Thursday, September 07, 2000 12:25 PM
> To: MIDRANGE-L@midrange.com
> Subject: Re: domain validation for e-mail addresses
>
>
> a dot to the left of the domain and everything else
> left of that dot is not part of the registered domain.
>
> So when looking up a domain like us.ibm.com you want
> to strip off 'us.' before looking it up.
>
>
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