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NO IMAP connectivity to exchange 2003 server inside LAN

Posted on 2010-09-04
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Last Modified: 2012-06-27
Experts, I have already ask this question and thought the issue was resolved but it is not. I am the full-time network admin over a Windows SBS 2003 box at my church. The server is running Windows SBS 2003 and exchange 2003 service pack 2 and the problem is If I'm inside the LAN, trying to connect to the exchange server via IMAP,  I cannot access the users exchange email. However, If I go outside the LAN, for example from someone's home, using the same set up they can access their exchange mail account via IMAP.
All the clients desktop are using Outlook or Entourage with an exchange server setup and sending/receiving email with no problem. I thought about creating a DNS record listing our mail server name, but when I try to do that, I cannot create (for example) mail.mymail.org...it ends up being mail.mymail.org.internalnetname.net. How can I setup IMAP so it works inside the LAN?
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Question by:Houston Blancett
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Expert Comment

by:sunnyc7
ID: 33605185
On your sbs box
Start run dnsmgmt.msc
Create an a-record for the imap server in outlook and assign it the lan ip address of the sbs server
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Expert Comment

by:btdownloads7
ID: 33605204
Whoever your ISP is (and it's probably AT&T), their modem is blocking loopback connections. That means that you can't access your own FQDN (mail.mymail.org) from withing the LAN. The easies thing to do would be to create a DNS entry that will resolve your FQDN to the internal IP of the exchange server. That will have no effect when the computer is outside your LAN, but when you are inside the LAN, it'll tell the computer to  connect to the server's internal IP, and therefore bypass the loopback block.
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Author Comment

by:Houston Blancett
ID: 33605215
I totally agree with both comments, but here seems to be my problem...my mail server is mail.xxxxx.org.

Ok my internal domain is mydomain.net (don't ask me why...previous admin created this). Now when I'm adding the A record, windows sbs wants to append "mydomain.net to everything, so my A record comes out looking like this...

mail.xxxx.org.mydomain.net. If I create that record, will it still resolve as you are both suggesting?
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by:btdownloads7
ID: 33605228
I'm sorry, I didn't make myself clear -- don't create an DNS record pointing to the internal name of the server. Point it to the internal IP address of the server.

Also, what you are describing (mail.xxxx.org.mydomain.net) doesn't sound right at all. Internally, your server address should be in the format "servername.internaldomain". So if your internal domain is "ourcompany.local" and the machine name of the server is "server", the address should be "server.ourcompany.local". I asssume that your internal domain is "mydomain.net" since your server wants to add that, but that really sounds like whoever set up the server originally did it wrong. You never want to create a domain that might resolve to an external internet address. That's why internal domains usually end with a ".local". And the way you have it set up, any computer (including the server) on the LAN will constantly try to connect to the external "mydomain.net" web address every time.
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Author Comment

by:Houston Blancett
ID: 33605244
Yes you are correct. Whoever the consultant or pervious admin was that set up the server, did not do it correctly. So just so I'm clear, when I finish adding this A record pointing to the server IP, it will look like this...

mail.xxxx.org.mydomain.net

And that's ok?...it will still allow the IMAP clients to get their exchange email within the LAN?
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by:btdownloads7
ID: 33605251
No, especially since the internal domain is not set up correctly. The record should point to the IP address NOT THE NAME of the server. So assuming that the external address of the server is "mail.xxxx.org" and the internal IP address of the server is 192.168.222.1, the record should be like this:

mail.xxxx.org --> 192.168.222.1
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by:btdownloads7
ID: 33605258
Also, don't forget to clear the DNS cache both on the server and each computer on the LAN
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by:Houston Blancett
ID: 33605269
Here's a screen shot of what I'm seeing...see what I mean. It is pointing to the internal server IP but look at the name of the entry. THAT'S what I'm confused about.
Screen-shot-2010-09-04-at-9.23.0.png
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Expert Comment

by:Emptyone
ID: 33605650
Do get this to work you will have to add xxxxx.org as a domain in DNS. That will help you to be able to make a A-record called mail and that will then answer to mail.xxxxx.org. But this will also mean that you will have to manually add all DNS records that are on the DNS servers that are hosting xxxxx.org today.
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by:sunnyc7
ID: 33605692
Create another dns zone for .org and add the lan ip of sbs with the imap server name
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Expert Comment

by:martinnolan
ID: 33606070
you could also add an entry to the host file which will do the same trick, look at

http://en.wikipedia.org/wiki/Hosts_(file)
http://accs-net.com/hosts/how_to_use_hosts.html
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by:btdownloads7
ID: 33609618
The hosts file can't be done -- first of all it'll have to be done on every computer on the network, but more importantly, it'll affect the computers even when they are outside the LAN, and once they are outside the LAN, they couldn't connect back to the server. It has to be done with DNS.
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by:martinnolan
ID: 33609787
sorry thought this was just to allow the dns to lookup correctly from one box.
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sunnyc7 earned 500 total points
ID: 33610714
hosts file wont work for another reason.
When you take the notebook out of the lan it will try to look for internal LAN IP @ as IMAP server.

I think the best way to do this is create another zone

mail.domain.org in DNS
add the IMAP server name - A-record within that.

If you are trying to create - mail.domain.org within -- domainx.net
it will end-up as

mail.domain.org.domainx.net

that defeats the purpose.
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Expert Comment

by:martinnolan
ID: 33610785
ok so not the best way but a host file would prove that the ip routing would work should the time to set-up the dns was done.
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Author Comment

by:Houston Blancett
ID: 33613013
I'm out of the office today, so I'll try the DNS host resolution tomorrow and let you know the outcome.
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Author Comment

by:Houston Blancett
ID: 33621861
OK just created a new zone named mail.xxxxx.org but unsure of what to name the A record.  Would I also name the A record mail.xxxxx.orgb pointed to the IP of the IMAP server?
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by:sunnyc7
ID: 33621931
Right click on the mail.xxx.org > New A-record
name
(Same as parent folder)
A-record
IP = lan ip
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by:sunnyc7
ID: 33627317
Did it work ?
thanks for the points
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