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Whose IP to use for MX Record (ISP or Hosting company)

Posted on 2004-08-18
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Last Modified: 2010-04-11
Experts,

Silly question but we currently have an outside firm hosting our mail.   We are implementing SBS 2003 and will be having mail hosted ourselves.  When we tell our current host to point the MX Record to us (our clients are currently using POP3 to grab their mail from our hosting firm) what IP am I telling them?

I have 2 different numbers?  One I got from our DSL provider 67.39.xxx.xxx (I believe this points to our router/firewall and then from there I need to forward port 25 to our internal server - 192.168.1.1) and another is from our current host which is 69.49.xxx.xxx

I assume I am using the first number from our DSL provider?

I am just confused about where to have the MX Record point to now so we can recieve mail.

Thanks
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Question by:mkavinsky
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by:PsiCop
ID: 11831280
The 192.168.1.1 address is a private, non-routable (across the Internet, at least) address. Putting that in your MX record will prevent anyone from being able to send you E-Mail.

Use the 67.39.xx.xx and forward port 25 traffic to 192.168.1.1
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by:PennGwyn
ID: 11832362
Your POP clients do not use the MX record.  They *can* be using a DNS entry, though, such as "popserver.yourdomain.tld", so that the clients will "seamlessly" start goin to the internal server when this DNS entry is updated to point there.

The MX record *is* used by remote SMTP senders to find out where to send mail for your domain.  So bring up your internal server and configure the port forward, and only when you update the MX record to point to your DSL will inbound email start coming to your new server, and stop going to the hosting company.

Suggestions:

1.  You might want to use something like fetchmail (runs on Linux) to collect any leftover email on the hosting server and deliver it to the new server.

2.  DNS information tends to get cached all over the Internet, so in fact while email may start coming to the new server almost as soon as the MX record changes, it may not STOP coming to the hosting company for 8-24 hours, or perhaps even more.  There are a couple of ways to try and "fix" this, but they don't solve the problem of users who have some messages waiting on one server and some on the other -- so I recommend that you set up fetchmail or an equivalent to solve THAT issue, and the DNS caching becomes unimportant.

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sriwi earned 250 total points
ID: 11866815
In your DNS server,create a mail-exchanger record that points to your Current static IP ( 67.39.xxx.xxx ).

On your isp, get them to point to you (mx records of your domain to points to your server) ( 67.39.xxx.xxx ).

Forward port DNS (53), smtp (110),pop3, to your sbs server.

you all set.

All user name will be active directory driven, make sure your active directory is correctly setup.

With client on laptop, you can get them to use OWA, and just give them ( 67.39.xxx.xxx\exchange)


Cheers
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Expert Comment

by:leeman928
ID: 14496662
A little mistake from sriwi...

DNS=port 53
SMTP=port 25 (not 110)
POP3=port 110

Leeman
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