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Open Apple Mail.
In the menu bar, navigate to Mail > Add Account...
Click the radio button for the Other Mail Account... option. Click Continue.
Fill out the fields as listed below and click Sign In.
Name: any name you want
Email Address: your.email@uconn.edu/shared_mailbox_name@uconn.edu
Password: your personal NetID password
You should now see a new dialogue box to add the shared mailbox with the message "Unable to verify account name or password." This is normal; you now have access to the extra configuration options, so fill them out as follows:
Email Address: (leave as is)
User Name: (leave as is)
Password: (leave as is)
Account Type: IMAP
Incoming Mail Server: outlook.office365.com
Outgoing Mail Server: smtp.office365.com
You will be asked which apps should use this account; mail is the only necessary one for this task.
The mailbox will be added to the Mail client, but you will not be able to send mail. To continue setup, go to Mail > Preferences.
In the Accounts menu, click on the account you just created (default name is "UConn"). In the Email Address field, click the dropdown and select Edit Email Addresses...
Double click on the email address to edit that field. Remove your.email@uconn.edu/ so that only the name of the shared mailbox remains. Click OK.
On the Accounts screen, navigate to the Server Settings tab along the top. Under the Outgoing Mail Server (SMTP) section, add your firstname.lastname@uconn.edu email as the User Name and click Save. The final settings should appear as below:
You can now exit the Account Preferences menu and return to Apple Mail.
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