Hi Augie Gonzal,
Now I understand you, You want to migrate one user to O365 and others still stay at original place , Both of them will use the same domain and all can work normally.
You can see link below as reference:
http://community.office365.com/en-us/wikis/exchange/simple-domain-sharing-for-smtp-email-addresses.aspx
Best Regards,
Jacky Ding
Now I understand you, You want to migrate one user to O365 and others still stay at original place , Both of them will use the same domain and all can work normally.
You can see link below as reference:
http://community.office365.com/en-us/wikis/exchange/simple-domain-sharing-for-smtp-email-addresses.aspx
Best Regards,
Jacky Ding