Receiving mail from two different domains

Receiving mail from two different domains - Fix A Problem | Google Groups:

"You can use a domain alias for your second domain. Email sent to
userna...@seconddomain.com will be delivered to username1. Likewise
email sent to userna...@primarydomain.com will also arrive in the same
mailbox, i.e. that of username1. Domain aliases are used for email.
The other GApps are available to the users through your primary domain
that is registered with GApps. See the following for more information.
You will need to set up the MX records for your second domain.

http://www.google.com/support/a/bin/answer.py?hl=en&answer=53295

Larry - Power Poster"