...
To add a mailbox manually from the main Outlook screen
Right-click on a current mailbox in the left-hand column
...
Click on Data File Properties - This will prompt a window to open.
...
Click on the Advanced button - this will prompt another window to open.
Click on the Advanced tab
Click on the Add button, type the mailbox name & click OK
It should then appear in the mailbox list:
...
Repeat for additional mailboxes
Click OK
Then Next & Finish
If you regularly send emails “from” the shared mailbox rather than using your own name, it is worth showing the “From” field when composing an email:
Create a New email
Click Options
Click From
This will then enable you to send an email “From” that mailbox, if you have access
...