If you have access to a shared mailbox and would like to send from it please follow this guide.
Open Outlook 2019 and click "File" on the Ribbon
Once open click "Add Account"
A dialog will then open. Add the Shared Mailbox's email in the "Email Address" field and hit connect.
A Security Dialog will then open. In the dialog add your personal CCSNH Email and Password and hit "Ok"
Make sue you add your personal CCSNH email in this field not the Shared Mailbox Email. Ex: JSmith@ccsnh.edu
If done correctly you should then be able to select the Shared Mailbox Email in the "From:" section of a new Email