My company is using 2 different email servers. First one being the MS Exchange (On-premise) server 2010, for email domain - abc.net. The second one being the MS Exchange Online, for email domain - def.net. abc is the parent company, while def being son. Quite a number of users are having mailboxes from both, and for these users, their primary mailbox is abc.
Now, this user is having both email addresses - email@example.com, and firstname.lastname@example.org. Password for both email maybe different, as we are choosing auto configure for password in Exchange online. I already setup and configured email@example.com in his MS Outlook setting up as outlook anywhere. Setup is a breeze. However, how should I grant the mailbox permissions for firstname.lastname@example.org, so as I can add it as a secondary mailbox into the same outlook? Or any alternative simpler way?
Thanks in advance.