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How can Exchange work on SBS without DNS records?

By OliOliUmphry ·
If I sound a little uneducated,'s because I am.

I inherited a server running Windows SBS with all the typical roles setup including DC, RRAS, IIS, DNS and Exchange. The company I'm working for is changing their ISP which is going to give us a new IP address so I need to point DNS records to this new IP address.

The problem is....when I open the Forward Lookup Zone in their DNS I see no records for any mail routing(A or MX), and there are no POP3 or SMTP connectors configured in exchange.
I did notice that there was a CNAME record called "companyweb" pointing to servername.domain.local. Don't know if this is relevant but thought I should mention it.

I called the previous IT company and they told me that the mail is routed through a 3rd party spam provider called MXLogic.

Could someone explain to me how this works, or am I simply missing something? The IT service comapny offered only what I've stated. Nothing more.

Is the mail being routed to MXLogic's server and their pushing it to me? If so, shouldn't there be some routing between us?

Remote Web Workplace and Webmail is also setup and working.

Thank you in advance

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All Answers

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by bart777 In reply to How can Exchange work on ...

The company that you registered your domain name thru has you MX record. It is currently configured to point to MXLogic.

They clean the mail and tehn forward it to your server.

As for the DNS entries, you may not have ANY external entries in your server tables. None are needed as long as your DNS forwarders are configured correctly. When your local server cannot find an address in it's own tables it will query the ISP's DNS server for the resolution.

Now... When you change your ISP and get that new IP address you will need to contact MXLogic and let THEM know where to forward the mail to. They will then make the change on the mail server at their end and the mail will flow as it always has for your firm.

Next you will go into your DNS server and change the forwarders to point to the new ISPs DNS servers. NOTE: this isn't required normally. The old servers will work just fine. I have used other ISP's DNS servers in the past to keep a company going until the real addresses could be setup.

Hope this helps.

If you have more questions just ask away.

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by OliOliUmphry In reply to OK......

bart777....thank you so much for that reply.

I understand. You explained that very well.

I do have one question in regards to MXLogic forwarding to us.

How can they "forward" to an address that they capture to begin with.

example: I send an email to receives, cleans, then forwards it to

Wouldn't it go right back to them?

More curious than anything.

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by bart777 In reply to Ahhh!

If you are referring to a mial that is going to another person in the local domain, that mail never leaves the server. It just routes inside of the Exchange server itself. As for outgoing mail, it depends on how the server was setup. It may be sending direct to the target domain, or it may be configured to forwad the mail thru MXLogic. I would imagine it's just sending straight out.

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One more....

by OliOliUmphry In reply to Internal?

Thanks again. Very informative.

One more simple question if I may.

You say that no external records are needed if the forwarders are configured correctly. I'm assuming that's because the mail records are configured on MXLogic's end.

If I want the mail to NOT go through MXLogic's sever and point the MX records to my server, I MUST put the mail records in my DNS server, correct?

Because if not, then that goes against anything that I've learned up to this point.

But please keep in mind....I'm no expert.

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All you would need to do is.....

by bart777 In reply to One more....

Go to your domain registration company and have them change the MX record to your interet IP that you will be getting from the new ISP. They will handle the real world DNS for you. Your DNS server only needs to have the correct DNS records for your internal network and the correct forwarders and you're golden. You don't want your local server to do all of the DNS work itself. That would be too taxing on the box. When your server can't determine the target IP it simply queries the forwarder for the correct address and sends the traffic on it's merry way.

On a personal note, I wouldn't get rid of MXLogic unless you have either found a better spam\virus filter or you enjoy listening to your users complain that they get hundreds of spam mails and want YOU to clean them all up. Or if you have found a better vendor to supply this feature for you.
Dealing with SPAM can turn into a full time job, even in a small network.

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Got it.

by OliOliUmphry In reply to All you would need to do ...

Hmmm. Ya learn something new they say.

I thought that if I pointed the MX records to my servers public IP I HAD to have the corresponding external DNS records to match.

Thank's again for informing me. If everything your telling me is correct, and I have no reason to doubt you, then you've been a big help Bart.

I will, just for the sake of doing it, change my own servers DNS external records and remove the A and MX records and see if it still works. Plus, as you said, it would be less taxing on the server itself.

By the way, I don't WANT to get rid of MXLogic's services. In a nutshell....There was an issue with not being able to access their spam managing portal to loosen up some areas as the owner of this company had suddenly stopped receiving emails from a very important source(it was definitely on her end). All I could do, after checking to see if their servers IP address had not been blacklisted, was to question the spam filtering.

Again. thanks for your help. I think I have all that I need now.

Just for the record....It was NOT MXLogic's fault that we couldn't access the portal.

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Follow Bart's advise...don't change your SBS Box

by CG IT In reply to Got it.

DNS records. SBS CIECW wizard configures all the DNS records itself including Exchange MX records for your public domain name.

If you have a public DNS name server service which points your public IP address to your public domain name, then all you have to do is open up port 25 through your firewall to receive email. If you manually change your SBS box DNS records, then DNS might not work properly therefore Active Directory might not work properly as Active Directory uses DNS to work.

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Sure Enough...

by OliOliUmphry In reply to Got it.

Well I'll be a Monkey's Uncle!

I had recently setup Exchange Server 2007 on my own 2003 Server (not SBS, so no CEICW) and had configured DNS for the mail records as I always have. All was working well.

Removed the A and MX records and sure enough....still working well.

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