Re: DNS Lookups

[Larry Bolhuis <lbolhuis@xxxxxxxxxx>]

Jon,

 Are you looking up the MX records and then validating the host names 
in that list?

 Maybe I am mis-understanding what you're doing but MX is the only way 
to know for sure which servers are out there for a domain. Generally 
Frequently simply the domain name itself resolves correctly but 
mail.xyz.com would just be a guess. In sites I work on it's usually 
smtp1.xyz.com and smtp2.xyz.com and such.

 - Larry

Jon Paris wrote:
> I am using a small PHP program to perform validation on e-mail domain names
> using gethostbyname.
>
> I found that some domains (e.g. xyz.com) gave false fails, so I adapted the
> program to also try mail.xxx.xxx.  I'm still seeing failures on some
> addresses that are supposed to be good.  Any ideas on what else to check?
>
> Reason I need this is that sometimes I have to operate using an ISP that
> rejects all recipients if any one of them fails a DNS lookup.  They don't
> tell you _which_ one - so it can be a royal pain trying to isolate the
> problem address.
>
> Jon Paris
> Partner400
>
> www.Partner400.com
> www.RPGWorld.com
>
>