Exchange 2003 - 2010 Co-existance inbound mailflow

Can an Exchange 2003 and and Exchange 2010 from the same org be configured to allow inbound email for the same domain.

MX 10 = Exchange 2003
MX 20 = Exchange 2010

If MX 10 is unavailable mail will still be received for to MX 20
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Manikandan NarayanswamySecurity Specialist & IBM Security GuardiumCommented:

Well i don't think so that you can have two different version of exchange server for load balancing the inbound email for the same domain. Its either you have to use exchange 2003 or 2010. And the servers configured on MX records should be of same version. The Proxying & redirection works on site level. However having 2 different version of exchange server with MX records is something which i don't think is supported.

Simon Butler (Sembee)ConsultantCommented:
Exchange doesn't care where the email is delivered to. You can have email delivered to any server in the org, and those servers can be any version of Exchange.
Just ensure that the servers can see each other.

@ Manikandan Narayanswamy your entire post is wrong.
There is nothing to say that the same version of Exchange has to be used for the MX records, it doesn't matter. It is just SMTP, nothing else.


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Will SzymkowskiSenior Solution ArchitectCommented:
This will work but not simultaneously. DNS records do not have load balancing. So you are correct when mail1 is not available mail2 will be used. You will also want to make sure that your Reverse records are also configured to ensure that you do not get blacklisted.

CanOfWormsAuthor Commented:
Very good. Thank you for the clarification.
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