Mandeep,
If you created the domain libertypark.com with an info user then create a user alias for libertypark on the email.com and set it to point to info@libertypark.com, it would work. Make sure that you copy the libertypark@email.com user data files over to info@libertypark.com before removing the libertypark@email.com user.
1. Create libertypark.com domain;
2. Create a info folder in the libertypark.com\users folder;
3. Copy libertypark@email.com data files over to this newly created folder;
4. Open the userConfig.xml and search for libertypark and replace with info for all applicable occurrences (username, contact info, popup alerts, etc.);
5. Goto System Admin -> Manage -> Restore, select Attach user and enter info@libertypark.com
6. Press Restore
7. Remove the user libertypark@email.com
8. Create a user alias libertypark that points to info@libertypark.com
Any messages sent to libertypark@email.com will be directed to info@libertypark.com.
I hope this helps.