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Before moving mailboxes.<br />
<br />
Get the mail flow changed. This is done on your firewall, not external public DNS, unless you are changing the IP. Get your firewall to route all port 25 traffic to 2010 HUB server. <br />
<br />
Check <a href="http://www.simple-talk.com/sysadmin/exchange/upgrade-exchange-2003-to-exchange-2010/" rel="ugc">http://www.simple-talk.com/sysadmin/exchange/upgrade-exchange-2003-to-exchange-2010/</a>&nbsp;for full steps.
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Before moving mailboxes.

Get the mail flow changed. This is done on your firewall, not external public DNS, unless you are changing the IP. Get your firewall to route all port 25 traffic to 2010 HUB server.

Check http://www.simple-talk.com/sysadmin/exchange/upgrade-exchange-2003-to-exchange-2010/ [http://www.simple-talk.com/sysadmin/exchange/upgrade-exchange-2003-to-exchange-2010/] for full steps.

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Mkris9,<br />
<br />
&nbsp; &nbsp;So is it completely acceptable to have multple mx records for the same company.com pointing to different Exchange 2010 Servers? Keeping in mind that they will have different priorities. Is this tru event if the exchange servers are in defferent AD Forests as well?<br />
<br />
Thanks
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Mkris9,

   So is it completely acceptable to have multple mx records for the same company.com pointing to different Exchange 2010 Servers? Keeping in mind that they will have different priorities. Is this tru event if the exchange servers are in defferent AD Forests as well?

Thanks

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When adding a 2010 exchange server to a 2003 exchange environment when is the best time to change the MX records/public DNS to point to the new 2010 exchange server to have the least amount of down time? &nbsp; Should this be done before migrating mailboxes or after all have been moved?
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When adding a 2010 exchange server to a 2003 exchange environment when is the best time to change the MX records/public DNS to point to the new 2010 exchange server to have the least amount of down time?   Should this be done before migrating mailboxes or after all have been moved?

Exchange 2003 to 2010 migration external MX records

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.