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From: oz casey, Dedeal on 5 May 2010 00:29
Before I say third time yes you do need to create MX record, let me ask you
this. Are you managing your Public DNS ? normally ISP DNS servers do have
these records, as I am not sure what is your situation.

Simply you do not need to have MX record internally to route the mail all
you need is A record which gets created when you add the server in your
domain. MX record is preferred ( not required ) to receive mail from other
SMTP domains. Simply this record tells sender who the authoritative mail
server for given SMTP domain. If I need to sent e-mail to
"mail.ournewdomain.com" I will sent the mail via my mail server---> this
mail goes out to my ISP DNS servers and my ISP DNS servers will do recursive
DNS query to locate mail server responsible from SMTP domain
"mail.ournewdomain.com" Now imagine , my ISP DNS servers will ask other DNS
servers,

1. do anyone know who is the responsible mail servers for SMTP domain
"mail.ournewdomain.com"
2. At this point your ISP DNS servers ( or if you are managing Public DNS
server , not to confuse AD/DNS servers) should have record called
MX=mail.ournewdomain.com=X.X.X.X ( Public IP Address)
3. The IP Adderess corresponds to your MX record is given to my DNS servers
4. My DNS server pass this IP address to my mail server
5. My mail server do know the IP address and open telnet session on port 25
to given IP address X.X.X.X
6. This IP Address should configured on your firewall X.X.X.X = NATTED =
y.y.y.y ( This is internal none routable IP, something like 192.168.1.200)
7. Port 25 is open from your firewall to your mail server
8. Your mail server does SMTP handshake and either it receives the mail or
rejects it

Now short answer is yes you need MX records, A record and PTR record for the
new SMTP domain on public DNS servers, for other people to sent you e-mail.
IF you have no public presence that is MX, A, PTR record for the new SMTP
domain name, people wont be able to locate your mail server hence intended
mail wont get to you.

I tried to break the story in details hoping to pass SMTP basic handshake
process to others whom might need same question
best
ocd





"jad" <noreply(a)newsgroup.com> wrote in message
news:#OTmnj46KHA.5112(a)TK2MSFTNGP02.phx.gbl...
> Hi!
>
> Hope you can clear this one up for me....
>
> We have exchange set up with our domain and all is good.
> We need to add a second domain that will eventually be our primary
> address. This is hosted at a cheapy ISP.
> I have amended the mail A record to our mailserver IP. Do I need to create
> an MX record for the new domain too?
> Our MX record for our current domain is mailgate.ourolddomain.com. Do I
> need to create an MX record for the new one as mail.ournewdomain.com. ??
>
> thanks in advance for the help!

From: "Lee Derbyshire [MVP]" email a on 5 May 2010 08:08
Yes. It should be a public IP address, and in your public DNS. A server
trying to send you email via the internet will first try to get the host
name of the receiving server from the domain's MX record, then it will try
to resolve that name to an IP address using the A record.

"jad" <noreply(a)newsgroup.com> wrote in message
news:uyDikj66KHA.980(a)TK2MSFTNGP04.phx.gbl...
> Yes - I have created the new A record for mail with the IP address of the
> mailserver for the new domain. So if I put in mail.mynewdomain.com. as the
> MX record then this would resolve to the IP address in the A record?
>
> thanks for your help!
>
>
> "Lee Derbyshire [MVP]" <email a@t leederbyshire d.0.t c.0.m> wrote in
> message news:%23tSPlo56KHA.3184(a)TK2MSFTNGP05.phx.gbl...
>> You could do that. Or you could start creating the correct records for
>> the new domain. As long as the name in the MX record resolves to the
>> correct IP address, it will work. Have you created the A record for the
>> host named 'mail' in the yournewdomain.com domain? Does it point to the
>> correct IP address? If so, then I would use that in your MX record.
>>
>> "jad" <noreply(a)newsgroup.com> wrote in message
>> news:uIkeCi56KHA.980(a)TK2MSFTNGP04.phx.gbl...
>>> So if our current mailserver is mailgate.ourolddomain.com do I set the
>>> MX record for the new domain to that? (As that is where we want the mail
>>> delivered and we are retaining that domain too.)
>>>
>>> thanks!
>>>
>>>
>>> "Lee Derbyshire [MVP]" <email a@t leederbyshire d.0.t c.0.m> wrote in
>>> message news:%23KBC4Z56KHA.1888(a)TK2MSFTNGP05.phx.gbl...
>>>> "jad" <noreply(a)newsgroup.com> wrote in message
>>>> news:%23OTmnj46KHA.5112(a)TK2MSFTNGP02.phx.gbl...
>>>>> Hi!
>>>>>
>>>>> Hope you can clear this one up for me....
>>>>>
>>>>> We have exchange set up with our domain and all is good.
>>>>> We need to add a second domain that will eventually be our primary
>>>>> address. This is hosted at a cheapy ISP.
>>>>> I have amended the mail A record to our mailserver IP. Do I need to
>>>>> create an MX record for the new domain too?
>>>>> Our MX record for our current domain is mailgate.ourolddomain.com. Do
>>>>> I need to create an MX record for the new one as
>>>>> mail.ournewdomain.com. ??
>>>>>
>>>>> thanks in advance for the help!
>>>>
>>>> Yes, you need an MX record for any domain that you want to be able to
>>>> receive SMTP email.
>>>>
>>>> Lee.
>>>>
>>>> --
>>>> ______________________________________
>>>>
>>>> Outlook Web Access For PDA , OWA For WAP
>>>> www.leederbyshire.com
>>>> lee a.t leederbyshire d.o.t c.o.m
>>>> ______________________________________
>>>>
>>>
>>
>>
>


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