With Microsoft removing Basic Authentication in Exchange Online on 01.10.2022 (https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online), they remove the ability to add a shared mailbox e.g. via IMAP or POP. (see e.g. Exchange Delegate Mailbox in Mail.app or https://discussions.apple.com/thread/250105787)

Several attempts with different email / user combinations failed either with the Mail app trying to add the sign in mail account (again) or with an 'Unable to verify user or password' error.

Is it possible to add shared exchange mailboxes to the Mail app? If so, how?

EDIT: I am running macOS Big Sur (11.6.6) and Mail.app version 14.0.

  • What version of macOS do you have?
    – jaume
    Commented Aug 10, 2022 at 9:52

1 Answer 1


I've succeeded in adding a shared mailbox on Office365 in Apple Mail 16.0.

Steps to follow:

  1. Go to System Preferences > Internet Accounts
  2. Add a new account by selecting Microsoft Exchange
  3. After adding the email address for the account I was prompted by Office365 OAuth and filled in the account and password

I am running macOS Monterey 12.6.

I have been accessing the shared mailbox via IMAP protocol until MS deprecated basic auth.

  • 1
    This still does not work for me on Big Sur with MacMail 14. In your step 3, I get asked for the password of the shared account, which does not exist. When changing the mail address, MacMail tries to add the Mail account with which I have to use for shared mailbox authentication. This mail account is already added...
    – Stefan
    Commented Oct 26, 2022 at 3:04
  • Indeed when adding the « delegated account » | « shared folder » using it's E-mail then choosing « Sign-in with another user account » and typing credentials of my account it's simply connecting to my account not the « delegated » | « shared » one.
    – llange
    Commented Nov 11, 2022 at 8:34
  • Looks like the only way to overcome that issue whilst still using Mail.app is to Proxy IMAP requests through another process that implements OAUTH2 authentication. Eg. github.com/simonrob/email-oauth2-proxy Apple shamefully hasn't yet added that feature even in the currently latest MacOS Ventura…
    – llange
    Commented Nov 11, 2022 at 13:12

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .