On Wed, 22 Jun 2005 16:20:04 -0400, Rich Greenberg <[log in to unmask]> wrote:

>Is this normal?  Shouldn't there be a node that responds to 
>"Lsoft.com".

No.  You can only 'ping' a host by name if that host has an A (Address)
Record in DNS.  (You can always ping a host by IP address because no DNS
lookup is necessary.)

"lsoft.com" is our general domain name and does not correspond to any of the
many servers we have.  However when email is sent to *@lsoft.com the sending
server does a DNS lookup asking for an MX (Mail eXchanger) record.  An MX
Record does exist for lsoft.com, pointing to the designated mail server that
receives all that mail, namely vm.se.lsoft.com.

Mail addressed to apple.ease.lsoft.com also tries an MX lookup, which fails.
There is no MX record for apple.ease.lsoft.com.  So how does mail get there
(except from earthlink)?  If the MX lookup fails the sending mail server
does an A record lookup, which succeeds (because apple.ease.lsoft.com is a
"Fully Qualified Domain Name" or FQDN).  Mail is then sent to that server.
The same is true of peach.ease.lsoft.com, except peach has an MX record.

Anyway, back to the Earthlink problem, I'm getting hints that it seems that
Earthlink in their "infinite wisdom" may have deliberately disabled this
(internet standard) "fallback lookup" of the A record if an MX record is not
found.  Naturally this will break the sending of email to many hosts.  I
would guess that at least 50% of mail servers on the internet don't have MX
records, they only have A records.  I'm guessing this approach by Earhlink
may an attempt to prevent "zombie" smtp servers from sending mail out of
their network, but this approach is akin to throwing both the baby and the
bathtub out the window with the bath water, so we'll have to see how it
plays out.