In my previous post here, I went into the steps needed to bring up a Microsoft Live Exchange Labs environment.

Previously we had discussed the different options available when it came to hosted E-mail here.

Setting up a Google environment can be done it one of two ways. You can choose to maintain your existing domain to which e-mail is currently being delivered to or you can setup a completely new one like gapps.your-domain.com.

Allowing to pilot their offering using your existing domain sets you up for an easier migration path, if you choose to go with Google and this is the path which will be described below.

Once again after receiving a requested invitation from Google, we proceed to re-route e-mail.

Pilot Google Apps with email routing instructions are here.

Once you have verified your domain proceed to create an additional MX record in your DNS pointing to your existing mail server. This will be needed because as you route all your mail to Google, they will need to send e-mail back your way to accounts that do not exist in Google Apps.

• DNS Record Type: MX
• Host: routing.your-domain.com
• MX server: server1.your-domain.com (your E-mail server “A” record)
• TTL: 3600 or 1 hour
• Priority: 0 (or High priority)

Setup Google to route e-mail back to your server.

• Navigate to the Email settings page in the control panel. In the Email routing section, the default destination is Google Apps Email.
• Click Add another destination to set up mail routing for your other system.
• Enter the MX record you created previously. routing.your-domain.com
• Deliver mail for: Select Unknown accounts only to route mail to email addresses that don’t exist in your Google Apps account.
• Change SMTP envelope: Uncheck the box since your other mail system is already configured to receive mail addressed to this domain.
• Save changes

Then you will need to change your MX records to route e-mail sent to your domain to Google mail servers.

Your configuration would go from something like this:

• DNS Record Type: MX
• Host: mail.your-domain.com
• MX server: server1.your-domain.com (your E-mail server “A” record)
• TTL: 3600 or 1 hour
• Priority: 0 (or High priority)

to this

Priority	Mail Server
1	ASPMX.L.GOOGLE.COM.
5	ALT1.ASPMX.L.GOOGLE.COM.
5	ALT2.ASPMX.L.GOOGLE.COM.
10	ASPMX2.GOOGLEMAIL.COM.
10	ASPMX3.GOOGLEMAIL.COM.

You are all set. As you create accounts in Google Apps, e-mail will be routed to their servers and e-mail will be delivered to those accounts. Any accounts non-existent will be routed back to the original e-mail server.

The diagram below makes it easier to understand.

Again there are lots of customizations including adding CNAME entries to your DNS allowing you to change the URL users will use to access e-mail and all the other options.

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