What is the differences between a Shared Mailbox and a Distribution Group?
The differences can be illustrated as follows:
Users in a Distribution List will receive their own copy of any emails sent to the Distribution List's address.
When replying to an email received through a Distribution List, the reply will be sent with the user's email address. Mail cannot be sent from the Distribution List's address.
Deleting an email received through a Distribution List will delete the email only for the user who deletes the email.
A single copy of any emails sent to the Shared Mailbox's email address will be stored in the Shared Mailbox's Inbox and can be read by any user with access.
Users can also be given "Send As" permissions which will allow them to change the address in the "From" field of an email they write. This will send the email from the Shared Mailbox's address.
Deleting an email from a Shared Mailbox will delete the email for all users who have access to the mailbox.
Shared Mailboxes cannot be accessed on a mobile phone, only in the Outlook application on a PC or OWA in a web browser.