Shared mailboxes do not have a password associated to them so they cannot be setup using the normal procedure. They can however be setup using the credentials of a user who has access to the mailbox.
I have used Office 365 as an example in the steps below but they are the same for any Exchange host (you will just need the Exchange server details)
Host: Office 365
Domain: mydomain.com
Shared Mailbox Name: [email protected]
User Account with Shared Mailbox Access: [email protected]
- Open Settings
- Select Passwords and Accounts
- Select Add Account
- Select Other
- Select Add Mail Account and fill out the required settings
- Name: Give a unique name (can be anything you like)
- Email: The email address of the shared mailbox(e.g [email protected]
- Password: Enter the password of the user account that has permissions for shared mailbox
- Description: Give a unique name (can be anything you like)

- Select IMAP and fill out the required settings
- Incoming Mail Server
- Host Name: Exchange server (e.g outlook.office365.com)
- Username: Username of account with permissions/shared mailbox name (e.g [email protected]/sharedmailbox)
- Password: Password of the user account that has permissions for shared mailbox
- Outgoing Mail Server
- Host Name: Exchange server (e.g outlook.office365.com)
- Username: Username of account with permissions to shared mailbox e.g ([email protected])
- Password: Password of the user account that has permissions for shared mailbox
- Incoming Mail Server
- Click Next

- Turn on Mail and/or Notes and click Save
