Question : Two e-mail addresses for one user

We have added a new company to our existing company, and with this company comes a new domain.  I need to add an additional domain to our e-mail system that can be used in conjunction with our existing e-mail addresses for our existing active directory users.  I have configured a recipient policy and have everything setup in exchange.  I need to be able to get and send e-mails through this domain to my existing users.  I have tried just adding an additional e-mail address to my existing user's e-mail addresses, but this only works for receive.  I need to send out these e-mail addresses too using outlook.  What am I missing??

Answer : Two e-mail addresses for one user

You can setup a secondary OU to to create new users for the new domain in and then assign a custom attribute to identify the new domain.

Then change the recipient policy to select users based on the custom attribute to make sure these users pickup the new domain name in their email addresses.

Depending on the number of users you have you can setup a one-to-one mailbox forward for all mail received in the second domain and create send as permissions for a user in the old domain on the new domains account.

This gives them the ability to select a secondary send as account when sending emails.

If this is not enough information to help you, please let me know and I'll expand, or if you have hundreds of users, then it may not be a workable solution.