One domain, same user with multiple email accounts w/ separate inboxes

Hi TClarkNRI,

It is not feasible to set up two primary email addresses or separate inboxes for a single user in Office 365.

As a workaround, after syncing the user to the cloud, you can create shared mailboxes with additional addresses and then assign full access and send as permission to the user. For the detailed information, you can refer to the following article:

Create shared mailboxes in Office 365

Please feel free to let me know if you have any concern.

Regards,

Frank

Hello Frank,

If we do it that way, would the user still have the option to reply as which ever email addressed they wanted?

Hi TClarkNRI,

Yes, the user can send and receive emails from both the primary mailbox and shared mailbox.

Regards,
Frank

Hi TClarkNRI,

Please feel free to let us know if you need further assistance.

Thanks,

Ran

Frank,

Tried this, but I keep getting the error below.

The value "*** Email address is removed for privacy ***" of property "UserPrincipalName" is used by another recipient object. Please specify a unique value.

Hi TClarkNRI,

Based on the error message, it seems *** Email address is removed for privacy *** is being used by another object in Office 365. Have you tried using a different address for the shared mailbox? And meanwhile, please have a try with PS cmdlet to create a shared mailbox via following article to see if there is any improvement
https://technet.microsoft.com/en-us/library/jj150570(v=exchg.160).aspx (go the last section of the article to use PS cmdlet to create shared mailbox)

Thanks for your time.

Best regards,
Ran