Exchange 2010: Two email domains on one mail server?

[+Cryton Subscriber²]

Hi all,

In my Windows network I have two Edge Transport Servers running Exchange 2010. They are currently configured to send and receive email using @mycompany.com

Currently I have MX records set up for @mycompany.com pointing to my two Edge Transport Servers; ETS1.mycompany.com and ETS2.mycompany.com

My A records for ETS1.mycompany.com and ETS2.mycompany.com point to the respective IP's of the edge transport servers.

I now have a requirement to also send and receive emails using @othercompany.com

I have registered @othercompany.com and am now trying to figure out how to set up the MX and A records for this new domain.

Should I configure them to point to ETS1.othercompany.com and ETS2.othercompany.com and then set the A records for ETS1.othercompany.com and ETS2.othercompany.com to the IP addresses of each edge transport server?

Will it be a problem if two different MX records resolve to the same IP address, or that one IP address will resolve to two different MX records for two different domains?

My edge transport servers are not on my domain (they're in the DMZ) but I didn't configure them when they were first installed so they're a bit of a black hole in my knowledge; is there anything I should be aware of in their regards?

Thanks for reading.

[georgevella]

No it's not a problem to have two diff. domains with their MX record pointing to the same IPs. What you will need to do tho is tell Exchange that it will start processing messages from this new domain and set up the user mailboxes appropriately. Unfortunately I don't have an exchange machine locally so I can't help you out with the configuration settings, but if I am not mistaken, it's something related to the delivery policies.

[Mordkanin]

No it's not a problem to have two diff. domains with their MX record pointing to the same IPs. What you will need to do tho is tell Exchange that it will start processing messages from this new domain and set up the user mailboxes appropriately. Unfortunately I don't have an exchange machine locally so I can't help you out with the configuration settings, but if I am not mistaken, it's something related to the delivery policies.

Organization Configuration -> Hub Transport -> Accepted Domains

[sc302 Veteran]

The mx records for othercompany.com should point to the same A records as the mycompany.com mx record to make life easy on you if you ever need to change A record ip's later.

After that simply tell exchange to receive for othercompany.com by adding it into the hub transport. That is it as far as exchange goes, but you may have to do additional work with your spam filter or service if you have one.

[+Cryton Subscriber²]

Thank you all for your comments - tomorrow will be an exciting day for sure :-)

[netsysllc]

You should add the domains as UPN suffixes in Active Directory too. AD Domains and Trusts, right click on AD Domains and Trusts, choose properties and enter the domains.

[duddit2]

Also add email addresses for new domains on the users that you want to have email addresses on the new domain, using either manual method or policy (if these are separate users, put them in a new OU in AD then use the policy filters in exchange to only give out these addresses to users in the new OU).

[Roger H. Veteran]

Unless someone knows of a built in way, the main problem you'll have is users SENDING email as @othercompany.com.

You can receive both no problem but whenever you send it will ALWAYS* be from @mycompany.com

Now I found a little app for this and apparently there is more out there (I don't work for them, just saying) but seems it would do the trick:

http://www.ivasoft.biz/choosefrom2007.shtml

I'm gonna test it out this weekend but someone sent it to me that's been using it elsewhere. If you folks know a better (free?) alternative then surely, let us know.

[sc302 Veteran]

You can set your default smtp, but that will be only one or the other. There is no way for one user to send as the other company, unless you create another user, give that user the email address of the other site as the primary and you enable the send as permission to your user for that other user.

User1@mycomany.com has the send as permission of user1@othercompany.com

[duddit2]

You can use policies to set email addresses and set the default SMTP address allowing you to give your users multiple email addresses and set one as the primary address (where email is sent from), but as stated above your users will not have the option of sending from different email addresses.

So user A logs on and opens outlook, without them knowing you could have added the following address and they will receive email sent to all of them:

usera@yourcompany.com

usera@anothercompany.com

auser@yourcompany.com

auser@anothercompany.com

Only one of these addresses can be set as the default SMTP address which is used for sending, now if your users have the need to send from multiple addresses, you can setup shared mailboxes and give them full access along with send as permissions, this additional mailbox will be added to outlook as a separate branch of folders.

[win2000b]

You could create an email policy for 1 mailbox store to be default of @yourcompany.com and the other store to be @othercompany.com. Then move the mailboxes that need to send as other into it.

Breaking down the stores to smaller manageable ones is always recommended anyway.